What huge mistake did you make early in your career?

My biggest mistake, that I made again and again, was not leaving a job when it was time. I thought I had something to prove, but there was never any point to it. You don't owe anything to an employer. You can't prove anything to an employer. They have absolutely no loyalty to you, and care less than nothing about what is right or wrong, wise or foolish.

So: If you ever think things might not turn out as well as you hoped, move on. There is so much else going on in the world that is at least as interesting as what you are doing, where you have a much better chance of making a difference, that spending time on things that you might not end up proud of is a terrible waste of your short time on Earth.

At my first real technology job I worked at an early web hosting company. Cutting edge stuff in 1996. We hosted full domains for $60/mo and tilde domains (e.g.; domain.tld/~myname) for $25 or $30 per month.

We hosted on BSDi, a proprietary BSD and every domain customer had their own sub-directory with user and group ownership.

As an aside, BSDi would happily let you run `rm -rf .` and would walk up to root and back down through every sub-directory deleting everything on its way.

One day, probably a month or two into working at what was my dream job, I accidentally ran `chown -r zelphyr .` in the parent directory where we had all our domain customers instead of my personal domain directory. (I can’t remember why I was doing that.)

Instant panic. I just knew I was going to be fired. I sheepishly went to my boss, Todd, and told him what happened. He grinned and exclaimed, “Cool! A challenge!” and had me sit next to him while we wrote a Perl script to look at the paths in /etc/passwd and chown that directory back to its original user.

I’m eternally grateful to Todd for being such a great boss.

Edit to add: in reality, my biggest mistake early on was not learning fundamentals. How binary and processors work, how machine language works and how higher level languages compile down to machine language. I would be a much better programmer had I done so sooner.

Held too many strong opinions for really no good reason other than technical "virtue signaling" of sorts. At the time, it felt so right. I had all the perfect, rational arguments.

Years passed, experience and nuance decayed the strength of my opinions, and it was fascinating to realize -- even where I was perfectly right, I was mostly only right accidentally, my arguments were just a story to fit the narrative, never really fully internalized.

I was a teenage intern, and my software engineering team was crunching in the evening on a project, when there was a problem on a workstation.

The sysadmin was gone for the day, so I was asked for help.

I saw the root filesystem was full, partly due to a bunch of junk files in `/tmp/`, including some files/directories that started with `.`...

You might guess where this is going, when someone hadn't yet developed good intuition for what was safe and not. At some point in cleaning up (and not having filename completion in that shell), I cavalierly typed:

    rm -rf .*

When the command was taking too long, I got a sinking feeling, and hammered Ctrl-C, while in parallel realizing exactly why it was taking so long. (Spoiler: `.*` matches `..`, so `rm` went up the filesystem tree, to `/`, and then tried to go depth-first traversal through the entire tree.)

It gets worse. This wasn't just a workstation -- this was a Sun Workstation, in the era of "the plethora of NFS dependencies is the computer". IIRC, either `rm -rf` started following the NFS automounter symlinks, to delete files from servers that it could, or an ad hoc NFS server had been set up on that workstation for some team purpose. Either way, `rm` hit files shared by multiple people, who were already working into the evening on a project.

It was the fault of the intern, who was both inexperienced and overconfident, and my team was really nice about it. Maybe they knew I regretted it so hard that, if I survived the next few minutes, I'd still regret it many years later.

Thought that I could replace lower-than-average communication skills with higher-than-average technical skills.

The story goes that software engineering is about knowing how to design a system a build it.

The truth is: you also have to know how to _sell_ your design, how to document your decisions, how to push forward with your agenda. You won't go anywhere without a team that values you. This means that interpersonal and communication skills should be valued much more than what I thought they'd had to be.

The most important part of a person is their relationships (you're not convinced? Try this exercise: describe yourself without mentioning any single relationship or its effect on you. What remains?). This is true both outside and inside your job. Value building strong and good relationships.

I created a 2x10 gigabit loop directly to the data center core of a regional health system on the consolidated virtualization rack that held ~80% of the applications back in 2012. It also took out the PBX. Thankfully it only took me just about 5 minutes to realize what I had done and run from the office area to the data center (in the same building thankfully) to set it back.

I thought for sure at minimum I was at least going to end up in a high pressure meeting about root cause and so on... no doctors complained, no ticket was ever created, the only mention that was ever made to me was "heh, was it you that broke things?" as the SAN guy was heading to his car and I ran past him.

Apparently 4:25 PM is a better time to break everything in a hospital system than the 2:00 AM change windows they schedule and nobody is going to bother calling support when things are working again by 4:30 and they just want to end the day. Service desk guy laughed at me when I apologized and he said he had 0 calls about it by 5:00.

So many. But it all boils down to not understanding how commercial software gets built.

I changed careers and did a 4-month “boot camp”. All the real learning was after that, the hard way.

My first job, I was left to work on a government project by myself. Everyday was mild panic. My only interaction with my boss was a weekly email saying what percentage of the project was complete. No one ever looked at my work, or cared to look. So I bumped it up a few percentage points every week. I declined a permanent position after the contract was over to spare the embarrassment of the state of the project I was building.

After that, I got hired by a consulting company. Over and over again, my total lack of experience was causing issues with clients, and I was in a daily state of stress and anxiety for 2 years until I was let go.

Finally, I got a job building enterprise software, with a well-defined lifecycle, and got my career on track. Eventually I became team lead. Now I work on the Standards and Framework team, building foundational components, libraries and templates for the other teams.

You will make mistakes. They are valuable to you.

Tying my identity to the company I worked for. Tech-corporate culture incentivizes you strongly couple your sense of self with your company, which was frankly disastrous for me and for anyone else I've known to fall into the trap.

I could see my company struggle and fall behind, and I desperately wanted to help turn things around (after all, this company was part of who I was). I overextended myself, made bad engineering and interpersonal decisions, and burned out. Worse, I stayed at the company for far too long, thinking that I could really make a difference in the trajectory.

Reading the article about "keeping your identity small" helped me greatly in not making the same mistakes.

Perhaps it's not a huge mistake, but I definitely did not think through the pros and cons of getting a PhD. There have certainly been some benefits (e.g. being able to move from my home country to one I prefer), but the amount of forgone earnings and time working on problems all by myself (where I don't get the advantage of mentorship so much; profs really have checked out on coding since before y2k in the most part) is something I hadn't considered, especially considering how well situated I was having gone to a top school in the bay area for undergrad.

The advice I've learned and that I hope someone could use is this:

only do a PhD if you can't NOT do a PhD, or if you know some specific job that needs it.

Unless your curiosity and desires line up with a great research group, you put yourself in precarious situations, e.g. it's easy to just bounce from one crappy job to another, but trying to go from one advisor to another (especially at a different institution) is incredibly difficult and usually looked upon with suspicion (e.g. whether the original prof is unloading a crappy student).

Don't do a PhD for some external recognition, because it probably won't come unless you are near the top end of consistently top-tier publications every year (e.g. those mad men and women who publish multiple papers at OSDI / SOSP in a given year!). Far more likely you'll find yourself toiling on something to appease your advisor, and in those cases the end result is very underwhelming. Some institutions literally just ask you to hand in your office keys when you turn in your thesis to get your diploma and basically say "thanks for the years have a nice life!".

I worked in a large corp you know about in California.. as a loner with few colleagues, I was deep in some assembly language and other nerdy topics, and not great with culture and certainly still a visible rebel. Meanwhile, my colleague from Big School Nearby was hired as staff engineer. There was serious IP on the table and security was an issue always.

It turns out that my colleague had an appetite for money beyond his paycheck as a starting engineer, and was talking to certain third-parties that sold peripherals and such out of Silicon Valley; not massive money by today's standards, but not nothing either. My colleague it turns out was somehow providing inside information to whomever. I was not interested in all this sort of stealing and whatnot, but I showed my 'rebel' flag as a cultural thing at that young age and was viewed with suspicion by the security people for sure.

So the Senior Engineers of the department figured out that there was a serious leak one day, and my clean-cut colleague and I both had access to it. The engineering management literally stormed my office, but I happened to be out. I was called to the main office later and it was serious. I denied involvement (TRUE) but they could see I was not telling them everything. My clean cut colleague .. no idea, but I think he worked there for more than a decade after that, with raises. I was put on a secret black list and didnt last much longer.

I never told on my colleague, and he has a house in Marin now. I am certainly unhappy telling this story. Reflecting on it - that story is probably part of why I chose this nick on YNews.

Twice I have built entire full-featured applications and then not shipped them out of embarrassment(fear of failing I guess?). Both times, a few years later similar applications became very popular. Very recently one of them showed upon the front page of HN to high praise.

It's a mistake I'm still making, I guess, which is to assume that it could never "be me". It can be anyone. Just ship the damn thing.

My biggest mistake for most of my youth was that I valued technical complexity over business utility. As a result, I kept moving from one trendy thing to the next one in technology, skills and domains.

Very late did I realize that putting simple php scripting to good and right use is enough to make the same money as trendy job and skill hopping. (on average ... i.e. ignoring outliers)

Working for a company that exploits [mostly] kids/teens' attention while being aware of the long term negative psychological effects of such.

Getting too big for my britches, and thinking that recruiter emails = job offers. I quit a lucrative junior position that had just promoted me to mid level thinking I would have multiple big offers lined up immediately. After 6 months of desperately interviewing and going broke I ended up somewhere I could work my way back up, but I learned the hard way to never quit a job without another offer letter signed.

Biggest mistake that impacted my career was not having a "rolodex" or keeping up contacts with people I met over dozens of projects my first decade.

Biggest whopsie as a 15 year old building servers was starting a server with case covers off to check whether it boots, then dropping a screw on the exposed hard drive board. It left a neat trail of sparks and smoke as it bounced down. 200mb full drive of insurance company data burned in front of my boss watching.

Later in career, different place different times, my colleague and best friend ran a mistyped grep on prod server that tried to suck up all of the files content redirected into a single file. AIX in my limited experience is an unbelievably robust system - but it does Not handle root disk out of space well. Or at all.

Landing a first job while holing up with an acquaintance after escaping my birth family, and then trying to move to live by myself without realizing just how screwed-up a lot of my subconscious and worldmodel was (and some of you will have noticed that possibility already after reading “escaping my birth family”). Access to the city and not wanting to be more of a burden on my host were legit motivations, but it turns out that that much stress at once combined with the wrong kinds of weakness in handling results in going near-catatonic (at least externally) a few months in and getting fired.

Whoops! Oh, and there's that multi-year non-compete agreement… in the only thing I have experience in…

Fifteen years and several retry cycles later, someone who graduated twelve years after me now has the three solid years of full-time experience that I never got (in significant part because once you have a Résumé of Nothing, it stays that way), and just landed a job making about twice as much as I'm potentially going to be able to start making a month or two from now if I drive my context-switching ability and energy output right up to the limit.

Did I mention that getting access to healthcare to fix relevant issues was almost impossible for almost the entire time? At least I have a potential path to it now—and there's only a decade of backlog…

Don't do what I did and waste your life. You need a fucking real job. Do whatever it takes to keep it for long enough. Otherwise you lose.

(In fact I am not entirely coherent in my opinions on the matter, though—and the rule of equal and opposite advice applies…)

I went into programming PLCs for industrial applications.

Totally stagnant, backwards industry, were the platform suppliers basically make a living, handing in advances from 20 years ago to the industries suppliers in the walled garden.

Its stressful, every machine developed is a unicum, software reuse is widely not used and often not possible, due to the "lowest common denominator" setting up what can work for a team.

All good programmers leave the field as fast as they can. The others, who cant and are worth the salt, are in eternal fear of the A-day or G-day. The day one of the large valley software companies turns around and says "boo".

They could easily replace the whole infrastructure of used software for all machines involved and install a steam like software market place for industrial controller components. No more "laptop-guy" sitting next to the machine for half a year and "thats normal".

The only thing keeping this industry "alive" is the phobia of the great ones from anything "physical".

I tried to leave, but this job is like a taint on your resume. People will not touch you with a stick, cause normal software companies have usually made bad experiences with the "programmers" leaving industrial automation. There are actually companies who try to lock there programmers in, by teaching them a "unique" bad software development style. I had people explaining git to me as a hot, new thing in 2018, at a company were we suggested it 8 years earlier. Yes, that resistant to change.

In every company you come, you are viewed as a sort of union-busting freak of nature, because that is the only way one could be that "good" at making software. Obviously i must be possible to memorize a million globals, instead of packing them into objects and systematically develop my stuff.

And you have that moment over and over again.

In dubio pro rubicon.

Staying in the first company of my professional career for too long. I would have learnt more and earned more if I moved companies regularly early on.

I was at IBM, fixing a critical mainframe that had brought the entire check clearance system for the country down.

An angry customer was breathing down my neck, making idiotic suggestions. I was rattled.

He wanted me to try swapping out some component. I said no, I was 100% sure that was not the problem. I was laser focused on fixing this problem.

Turned out I was wrong. Customer complained to my management and I got a sound bollocking and took a couple of steps backwards in my career.

I learned that day to always remember that, no matter how unlikely, you might be wrong.

As a sidenote, this is one of the 25 points of advice in John Perry Barlows "adult principles" which I discovered late in life. It is the only written work I have on my wall, with items 1, 3 and 10 marked with highlight pen by my wife as areas for personal development for me.

Disdain for sales. My first exposure to a sales team was as an engineer that had to deliver on whatever requirements sales dreamed up. Several years of head-shaking bullshit and I decided that the entire vocation was worthless. Took me ten years to figure out the better approach is to build bridges there, not burn them down.

Co-founding a company without really understanding my personal exposure. Had a small consultancy that had some early success, I was personally billing and leading projects, hiring folks and managing them. CEO just stopped actually cutting checks to IRS for a few years in a row. This snowballed into a major issue that I was personally liable for. Unfucking that took 5-6 years of my life. Yes yes yes I'm sure some of you out there would have been auditing financials every quarter...I didn't. Maybe that's the second half of the mistake.

Getting comfortable. After the above, I was running the show and just got comfortable. No real growth but a good salary for myself and a few other folks. Turns our there are parts of running a company that I'm just not wired for and never got good at. Decided I should let someone else do that and shut the company down (long explanation as to why selling it wasn't a good option). Worked at a FAANG for a bit then took another job. Doubled my TC in about three years and think I should have probably done this a long time ago.

- Not leaving jobs often (even without clear immediate reasons).

- Not being aggressive about trying to get better salaries. This was mostly due to the previous point.

- Not leaving shitty managers and teams ASAP (“trying” is the biggest mistake in such situations).

But when I look real close then the single biggest mistake is:

- Having not identified early that Software/CS simply doesn’t interest me. It’s just a skill because I happened to study it and then started working. For me there’s just zero passion in it. And not trying to find an alternative career path early.

I decided to study electrical engineering instead of computer science because I was dead certain there was no money to every be made writing software.... in the 1980s!

I chose the wrong school because they accepted me, and my high school counselor thought I had zero chance. I couldn't afford it, and dropped out. I would have gone much farther studying computer science at Purdue Calumet, and could have had it all paid for.

Once I had the Windows NT 3.51 server drive mapped as D:, and got confused thinking it was a local drive. Had to drive 25 miles and rebuild things in the middle of the night, sweating bullets. We were a small ISP with 200 customers, I was the tech staff.

My next to last big mistake was staying at a system administrator job far longer than I should have.... they really didn't need someone full time, and it zapped my drive to get things done.

Then I took a job making gears... the pay and commute sucked, but I liked doing it. 5 years away from technology, then Covid hit, I got sick... and I've been tired ever since.

I stayed for almost four years at a job and in a location that I knew with great certainty was a poor culture fit for me by the one-year mark.

Similarly, I knew that I needed to do some therapy work, and deliberately did not do it so as not to end up with a diagnosis that could affect my potential admittance as a Peace Corps volunteer. (This was deeply misguided; the volunteers that did their work were both admitted and frankly more effective.)

Both of these mistakes were arguably the same mistake: I did not take care of myself. As a result, the first half-decade of my career was basically a wash. I burned out of the industry I went to school for, and a large chunk of time I could have spent deliberately learning and building was instead spent essentially coping and surviving.

I took down all cellular data traffic in Philadelphia for 2 hours.

I wrote the operating procedures for performing a backhaul upgrade in preparation for the launch of LTE. The upgrade was being performed on our primary routers which all traffic traversed. The operation had been performed several times successfully, but after the last implementation before the issue, I was informed that a couple of the lines were wrong (they had extra arguments). I did a find and replace all, shot the document off to the next team, and went about my day. The technician who was doing the upgrade called me on the afternoon of the upgrade (it was a Sunday) and asked if any of the initial steps were disruptive as he wanted to get started on the prep work ahead of the maintenance window. I said no and he proceeded. Mind you, this was also during the World Cup so I was out at a bar with my friends and not paying attention to my phone. About two hours later I looked at my phone and had multiple missed calls and voicemails from him, so I immediately ran to the MTSO. Turns out my find and replace changed some commands - the end result was that instead of adding additional VLANs to in-use interfaces, it replaced all of them with the new ones, which weren't carrying any traffic.

The fix was simple, we had failover routers and at some point after he couldn't get in touch with me the technician reached out to one of my peers who quickly told him to failover. He should have known to do that but he was also panicking. I called my boss and told him what happened and that it was my fault (and I genuinely believed it was. I wrote the bad procedure AND I approved activities outside of the maintenance window), and he told me to be at the office with the technician first thing in the morning the next day.

I couldn't sleep that night, this was early on in my career and I thought it was over. But that meeting ended up being one of the most transformative moments of my career. My boss's boss, a director, quoted the FAA's ethos of how a good system should have checks and balances, and if a mistake happens, the system is at fault, not any individual. We walked through the play by play and identified multiple opportunities to both avoid the issue that arose and to resolve the issue more quickly. We came up with an action plan as to how to make sure our "system" was more mistake proof for next time, and that was that.

That meeting has always stuck with me, and I always remind myself of that conversation whenever things at work don't go as planned. There is almost always something in the system that can be improved to account for human error, which should be expected.

Back around 2000, I was writing software patches for a large telecom company. These patches had to be applied to live, inservice telephone switches and equipment that were powering public phone services - restarts and downtimes were not an option. Needless to say, careful consideration had to be given with regard to how a patch was developed and applied.

I don't recall the specifics, but one fateful patch had a very large compound boolean expression that included an invalid condition. For whatever reason, that expression didn't or couldn't receive 100% test coverage.

When applied, this patch took down the entire phone service (including emergency 911) for the island of Newfoundland Canada and all its residents (maybe 300-500k people).

The immediate fix was simply a new patch that reverted the bad patch. Unfortunately, it took several hours from the point we learned of the issue to writing, delivering and applying the fix.

I've heard that Newfoundlanders have a reputation for being very friendly, so I like to believe that all has been forgiven and forgotten and that I may one day visit the island in peace.

In the old days as you approached 30 being a pure programmer was unheard of (or at least you were going to become that "weird guy" in a corner office) and you were expected to move into management / consulting

I resisted and became that guy. I would be far richer by now if I had put on a suit and gone into consulting. It's not like I didn't have offers

Keep an eye on your pension / savings when you are younger. It gets much harder to top them up the older you get. My pension options scare me now and I can't see retirement as a realistic path

Take money seriously!

Not keeping up with professional connections as I made them from the start. Even a "happy birthday" card would've been enough, but here we are.

Accepting a job with QA out of school. It was 4 months before graduation, and I had been searching 2 months and my morale was low at having been rejected a few times. I was a very good student with many accolades so rejection was new.

As it happened, 1 month before I graduated, a job opened up in my ideal group, one I had interned in before and gotten a strong review, but by then I had already accepted the QA position (at the same company) and it was impossible to transfer. Took me nine years to transition to being a dev, studying nights and weekends.

At least in the U.S., your first job out of school tends to become your "career"

I put too much effort into work which lead to a severe burnout that rendered me incapable of being useful and productive for years. I'm one of those guys who grew up using computers, every wake minute I was thinking about computer related stuff, everything had a solution using software in my head. I lost this from one moment to the other. Luckily for me it came back after 4 years of the crash. Fun times. Have a life outside of work even if it's just the same you do at work, but do something unrelated. People need to recharge their brains using activities they truly enjoy

Not taking enough chances. I've been doing this for over 20 years and there's only a couple of jobs I've interviewed for that I didn't come with an offer. I thought that meant I was hot shit until a few years ago, I realized that I was really just aiming too low.

Not putting the hostname or something distinct in my shell prompt, at least on my machine.

  sync && reboot
  Connection closed by remote host.

Mild panic sets in... Oh, lets up-arrow and see what customer server I just rebooted. Reboot on Solaris did not do a graceful shutdown of anything, it just sig-kills everything. Veritas clustering in it's early years did not like this one bit.

1) not spending enough time developing professional network.

2) Becoming too comfy with the position and not pushing the bar as hard as I could could.

3) Staying too long with the company.

4) thinking too well of how the rest of the business perceives my position.

Taking a job as a solo "lead" developer at a startup for my first job out of school.

I picked up so many bad habits and it took a while to figure out how to collaborate with others on code. If I had to take that same path again, I would get involved with an open-source project to solidify the fundamentals.

Reinventing the wheel. So many hours wasted on creating something that already existed in the form of PHP libraries or Python libraries that are written by much smarter folks. I tell my guys now, tools such as Ansible exist, don't try to write a whole Bash program to mimic what Ansible can do.

Commented out the credit card charging part of the order processing pipeline during testing and pushed it to production.

Used the x.25 pad (telnet, for an older protocol family before internet became ubiquitous) command on the console of a vax 11/780. The pad break-back sequence to get back to the calling shell was ^P which was alas also the vax break to halt/debug command if you were on the main console. Took down the entire campus interactive logins

In terms of a "whoopsie" without guard rails: lost data because I was in a production database and didn't create a transaction. But, to be honest, I shouldn't have even been able to do that in the first place.

Otherwise, I spent too much of my early career focusing on learning application development tooling, and ignored database systems. Often, a fantastic distributed, networked application is right there in your stack. A lot of good information comes from getting to know how these pieces work, instead of treating them as "magic black boxes".

A belief that as a JavaScript developer competence and a thorough understanding of the standards are a valued commodity. This is absolutely wrong. The name of the game is tools. Most people are scared to death of writing applications in JavaScript and absolutely hate the DOM and many other standard APIs, so… tools. If dicking around with tools and frameworks isn’t your thing look for somewhere incredibly niche to park your career.

I learned early to not be an architect unless you have the support of company leadership. If you do your job too well you are disruptive, people get sad, and then you are on your way out once the crying gets loud. If you aren’t doing that then you aren’t effective and the position should be eliminated. You can reasonably determine this during job interviews if you ask the right questions in the right ways.

My biggest mistakes were: - I loved studying CS. I was in a class with 5 other students and we had close interactions with the professor. After I took the exam, the professor asked me to become his assistant (not PhD but student). I turned down the offer because I would have needed to quit another shitty student job. In my case, this would have been an important experience for getting a PhD position though. - Taking one of the first offers after graduation and sticking with it for too long.

Maybe this advice is helpful to someone. Let's divide people into those who don't realize that they don't understand something and those who realize that they don't understand something. And into those who ask questions and those who like hearing themself talking/explaining.

Out of the four the combination of 'don't realize that they don't understand' and 'likes hearing themself talking/explaining' is horrible. Run away as fast as you can! You cannot do anything. If you ignore it: then, it leads to a bad project outcome. If you try to fix them: your relationship will deteriorate which again leads to a bad outcome and more.

On one of my first database projects, I developed an absurdly inefficient SQL database for time series data. Oh but it had a beautiful, easily generalizable, fully normalized schema which I was so proud of... Who cares that it requires a complex join before every insertion? And that multiple tables needed to be updated to keep track of metadata for each insertion?

It went into production without any load testing, and it struggled to keep up with even a few dozen time series.

I suppose the good news was that the product it was developed for never got many users, so it just hobbled along after applying some caching hacks. And of course I learned an important lesson about considering database access patterns.

Technically not a mistake but a good lesson anyway, db2 drop database dbname, where the production and Dev db had the same name just on a different VM. For a very long probably only 10s of seconds in reality I thought I had dropped the production DB of a securities and money market reconciliation system that was reconciling up to 50M a day at the time. Still gives me a shudder when I think about it 10 years later

I used a data migration tool that, unknown to me, reset the counter for auto incrementing indexes. I had used those counters for serial number fields.

There are hundreds (thousands? It’s been a long time) of high end bicycle components in this world laser etched with overlapping serial numbers because of me.

Non-technical - was too outspoken/somewhat abrasive and expressed opinions/ideas a bit too strongly. Of course it depends on exiting culture but in my case, it got labelled me as hot-headed and not "reliable" (even though objectively looking, some of the stuff I wrote is still being used). Perceptions form fast, are not always rational and pretty hard to break so it might be beneficial to observe more, express only when necessary and do so in an even and calm manner.

I didn't immediately end a meeting to demo a prototype when 2 out of 3 stakeholders were no shows.

I got lots of feedback from the remaining stakeholder that the other 2 strongly disagreed with.

In my new career as a freelance consultant / mini-agency: taking on a large fixed-price project. It’s not that the scope has changed - it hasn’t at all - it’s just that I judged it like shit.

Don’t do this, kids!

(Though many of you still will. I knew about this beforehand and still got myself into this mess. Never again!)

The biggest one I remember is telling everyone that I was logging off for the day, typing "sudo poweroff" and then wondering why my laptop hadn't shut down… turns out I was ssh-ed into our main production server which was not redundant and the whole system went down.

Thankfully my boss was understanding. I intercepted the on-call notice and took care of it before filing a report about how it happened which was probably helpful. I had pushed back previously against passwordless sudo as well and been overridden, so maybe they took that into account too. Still, I thought I was going to be fired for the mistake either way and am very thankful they didn't.

I learnt and worked on how to earn money, but didn't learn and work on how to grow the money I earned.

I worked at a really toxic job at a hedge fund where I let them burn me out in a year and then they fired me. Several mistakes were made:

1) I failed to realize the importance of face time/asses in seats time. I was spending tons of ime working late nights and weekends solving hard problems outside of trading hours where nobody could see the hard work I was putting in. Also, being the only hourly, all of my coworkers would disappear early Friday afternoon and everyone else senior in the department would ask me to do weekend work that would effectively have me working 2 days of overtime without going home. Essentially on Fridays I worked for 3 straight days without going home every weekend for 9 months.

2) I accidentally exposed an embarassing mistake made by several seniors in the department. A simple question that I asked in a meeting when I saw how two pieces of network gear were hooked up identified that if either went down we would end up with a network loop and a minor catastrophy for a very expensive trading system. Two of the network engineers in particular were really angry at me for this and would no longer speak to me afterwards. Apparently correcting the mistake took several weekends of off-hours work.

3) I let an absolute snake in the department "mentor" me when I was new. I failed to realize she was using me as an opportunity to reassign her work. When I got sick for three days with a sinus infection, she reassigned hundreds of her outstanding tickets she was delaying on to me and then started calling me out in department emails asking where I was and why I wasn't handling the tickets. Nobody bothered to look at the history before forming their opinions about me. Luckily, she's no longer in the industry and works as a baker.

4) I let the traders physically abuse me. One asshole spilt a cola on his Bloomberg keyboard and I was at his desk with a replacement within 5 minutes. Apparently I wasn't fast enough for his liking and he spent that few minutes kicking me in the ribs as hard as he could while I was under his desk hooking up the new keyboard.

5) I was addicted to World of Warcraft. Despite the long hours I spent at work, I unfortunately filled my free time with video games instead of finding a better job.

I worked for a company with an excellent mission but poor engineering growth opportunities for way too long.

I paid little to no attention to how my engineering efforts benefited the business.

I spent few years doing frontend while i hated it.

In '98 I uploaded an index.html for a subsection of the corporate site to the root, squashing the corporate home page in the process. We didn't have any source control or backups. I had a colleague who had the page open, and I was able to copy the code from his browser. Learned a lot that day!

Not starting with a big name tech corp or a high-growth VC-funded company. Big brand on CV makes big difference when recruiters are doing initial screening. A CS/MBA degree from top university helps. Do whatever you can to work with a big tech brand early in career, otherwise later you will regret.

I made a dumb mistake and got fired three years in. Instead of dusting myself off and jumping back in, I tried to pivot to a new career, went back to school, and just failed at all of it. Took five years but I made it back to my original career track and I’m finally back to where I should be.

My biggest mistake was not accounting for the ethics of what the company was doing.

I was young, and super excited to have a job in software while still in school, building things. Only much later did I realize that multi-level marketing (pyramid schemes), pay day loans and companies selling bath salts to smoke, all hurt people.

I was removed enough from the problem that I didn’t see it at the time, and it all seemed so exciting, but I certainly have lots of regrets from that time.

Invited a community of users to help fix bugs in software and accidentally implicitly bust the IPR of that software suite.

I behaved as though what I knew mattered more than who I knew.

Taking a year break in 2014.

I lost potential to earn a few millions from continuity of my career.

I also discovered I like coding and don't really enjoy traveling.

Traveling is romanticized too much in our culture.

Not joining organizations with an solid engineering culture (potentially a current problem depending on the next few months).

I'm relatively new (2 years experience), but haven't really had a chance to learn how to do many things properly in many cases due to a lack of more experienced people to learn from/business priorities meaning it gets waved away.

This won't get me fired in my current job, but the lack of knowledge might get me fired in future ones.

Picked up too many boring jobs with messy legacy codebases as opposed to prioritizing building and specializing. Went into industries that ended up being on their way down and didn't take care of their engineers and switched to tech late.

Under HP-UX, I had a script that did an "rm -rf *" once, prior to a cd.

A SAN firmware update (forcibly installed by a technician onto our hsg80) silently prevented my filesystem from mounting, so the rm ran from the root directory.

I got everything back.

Working for too long in a place where I was (literally) the expert. This was dotcom bubble time, so I ended up in a graphics firm wanting to get into ‘the web’. This inflated my ego, but left me without a proper mentor, or people to learn from. In retrospect it was fun, but mostly wasted time and we did so many dumb things and reinvented the wheel so many times I blush to think of it all now.

Staying too long at my first job. Held back my wages and career. Thankfully I am above the industry level now....but it took a lot of effort to get to it. Lesson: Never say loyal to a company. Stay only loyal to yourself.

Working on a ServiceGuard cluster of HP-UX boxes for a major retailer, I put the IP address onto the wrong computer, and stopped all warehousing operations (for the country) the day before a long weekend. Might have been a million dollars worth of losses incurred...

My brother short-circuited $25k worth of test equiment (at a time when salaries were around $30k/yr) on his first day at work at one job.

Believing that senior management had a legit plan for my career track. In actuality, they would have preferred the status quo as long as possible. I stayed 2 years too long in a 6 year gig; there were other manipulative issues from the boss on all his staff. You own your career progress/development 110%. Think like a mercenary and don't let anyone fool you otherwise.

Thinking I was irreplaceable and the business couldn’t continue without my expert system knowledge. Boy, was I wrong and it was eye opening.

Not going to to a software engineering heavy organization. Instead I went to a place where we had to justify using Java 8 instead of Java 7.

Launching a venture backed bespoke eCommerce website many moons ago using staging payment gateway credentials and not coming to the realization until a week later when the accountant asked me why hadn't any funds settled yet.

Boss threw his blackberry out of a high rise window shouting profanities in German while I shrunk into my chair experiencing waves of hot flushes.

Not seeking medical attention sooner. I have anxiety disorder and a large amount of unproductive times were due to mental health issues.

My excuse to.myself was "its not the right time" over and over again.

Working at the NSA.

I am no longer able to travel to mainland China out of concern for my safety. I work closely with hardware and the inability to visit Chinese factories is becoming a career limitation.

About 6 months into my first proper gig I was working on some code for emailing people in estate agencies. Typically you've got three channels, Rental, Sales and Commercial there. This was a Java Spring app and I didn't really understand all the annotation magic, and the channel field was nullable as to make it non-null you needed to write a @NotNull annotation above it. To add insult to injury I gave the field the wrong name too, it was agentChannel, not channel.

I then wrote some code like:

  if (channel == AgentChannel.sales) {
     emailSales()
  } else {
     emailRentalOrCommercial()
  }

So when parsing the JSON, the field name silently failed and all emails got sent to rental or commercial channels.

Sales is obviously the most lucrative channel with the biggest contingent of, shall I say, "pushy" people and so when this was discovered I had quite an upsetting day.

I would say not prepping enough for technical interviews. I did a lot of prep (hundreds of hours) but it wasn’t enough. I needed more because I was always being compared to senior engineers with 10+ years of XP who had been through the gauntlet a lot. Very few companies were ever explicating hiring for a junior or “mid” level role when I was looking. (Less than 3 years xp)

In the end, I realized I need to be doing interview prep pretty much all the time. Maybe give it up just before you start the next job and while you’re ramping up but it should just be routine once you hit 6 months or a year. There’s no reason to not do it because in all likelihood, you’ll be switching jobs.

I’m going into my sixth job in about 8 years now. I shouldn’t expect to stay at my next place longer than 2 years and thus should be prepping well before my planned time of exit.

Frankly, the biggest mistake of my career thus far has been starting it. I didn't get in to a university, so I bumbled around for 6 years at a community college. In the middle of it, I managed to get a 6-month stint at a help desk (which I needlessly proud of, and then promptly fired from). Went back to the community college, burned out on trying to get an associates and transfer, and tried changing course to getting some sort of certification. Ended up with a CCNA (which expires later this year), but it turns out nobody near where I live wants to hire a network technician or engineer without a diploma, and my savings aren't enough to move.

So now I'm in my mid twenties and I've only just managed to get an (unpaid, remote) internship thanks to a sympathetic small business owner whose pet technical project is falling behind schedule. Every time I open the project management tool, I feel a vague sense of unease because I'm socially tone deaf and I can't tell if I'm breaking some unspoken rule about "don't word this message this way because you'll sound too confident for an intern speaking to the senior developer," or "don't make a comment on this task because it's assigned to an intern on a different team and you're not supposed to go out of your lane."

I've been writing code of some sort for 11 years, and using Linux daily for 8. Every day I wake up in my childhood bedroom and send my one remaining friend a message. Sometimes she even replies. Then I have the pleasure of spending most of the day fighting with some stupid self-inflicted issue, like why Ethernet broadcast breaks every week on OpenWrt, or why Pulseaudio uses 200% CPU when I try to get it to communicate with a certain cgroup, or what I'm going to use when Fedora 33 hits end of life and I have to get some other DE set up to replace GNOME.

I've dug myself into a labyrinthine, unsatisfying, inescapable hole. So if I could do it all over again... I wouldn't, because, like a ball on a hill, I'd end up right back in here.

Rushing a job search. Decided it was time to move on (right decision), but allowed one company to court me and did not take enough time to play the field (bad decision).

It was 2006 and I was working at CollegeHumor, my first job after graduating from college. During my first week I dropped the production database. I thought I would be fired…

I ended up working there for 4 years and eventually managed the backend engineering team. I haven’t dropped a production database since.

Thinking the best course of action is to operate within the bounds of an existing paradigm, rather than lobbying for paradigm altering changes at the highest levels.

Buying into any zeitgeist at any level. Related: underappreciating the pervasiveness of financially-motivated thinking.

Didn't attend the hiring fair in my last year of uni, and missed the chance to become fully vested in Microsoft and like companies in the 1980s

Sent out the HBO Integration Test email this past week.

Joking

Joining a company out of college that I thought was good and staying with that company to this day (9 years later). I'm a midlevel making under $100k and was screwed over multiple times in contradiction to what the company promised and what the policies say.

Yes, I got one which affected me a lot.

It was a story about my last manager. 2 years ago, I transferred to Cloud team internally from blockchain. Yeah, both of them were so hot and even today. I had to make this transfer because I have to relocated to another city where my family resides. And my mom was so sick, I had to consider to take care of her. This is the background.

At the first few weeks, I tried to learn the new knowgede of cloud native and it was so depressed. I was so new and I was not an open man. Because my mother's health condition always makes me so gloomy. I could not be open. So it was not efficient. Well, I love opensource and I have some experiences. So I was assigned to do some open source projects for our products. Now here we have the them:

1. My manager called me to out of the opensource team for something else that I did not listened and not interested at that time. 2. He said this was his team and he was the only man can decide that no one could change.

I was a little shocked at first. And hated this then. But I could not change this. I knew the only way I changed this that I argued with him or leave. I knew at that time every body in our team had quarrelled with him. But I felt down at that time I could spare the energy to fight.

I made my mistakes. Not sure this was a mistake. I have no idea who things would went if I had a different choice. I chose to accept it even though I felt so bad. I could have choosen another blockchan startups.

So I had a bad 1.5 years work experience in my career. One interesting story:

My manager wants us to show our minds about team. Guys had their voices out and the summary sent to him, which were all agaist him. Can you image what he looked like?

He denied all the comments from guys. And continued to do as his will. Then 8 months later, our team was laid off, all but me. I had a health condition at that time.

It was a bad experience. I should not have hesitated. I should have called out my thoughts. Or just leave.

Life is short. Please stay happy and focus on the lovable things.

Took a first job that played to my weaknesses but was in a field I was intellectually interested in, rationalizing it was an opportunity to grow.

I rejected an $800k deal early in our company's life because it didn't involve licensing the existing software we had written — it was work for hire, which "wasn't our model." Looking back, that was pure stupidity.

I didn’t realise how important politics were and how far some people will go to crush you if you think you are a threat.

I had a senior co-worker tell me some documentation I had written was terrible, when I asked what was wrong with it he replied “everything”.

Months later I found much the same document (as in 90% of it was copy pasted from mine) in our company wiki, under his name.

I /think/ (thankfully such a situation has n out come up since) I should have raised this with him and more senior managment immediately instead of just sighing and moving on from it.

I also echo sentiments about not leaving early enough - if the ship is on fire, be with the rats, not the captain.

Not making attempts to grow. Skated along for over a decade on the same skillset, took whatever jobs came along. "Working to live" has its perks, but one of the drawbacks in this field is you can be slowly left behind.

Stuck too long only with Microsoft ecosystem.

I told a fairly obnoxious and (in my mind) idiotic customer to "take a chill pill" on a conference call. This did not work out well. I did call them back and apologized before my management told me too, but I'm claiming no credit there, that was just pure self-preservation kicking in. On the plus side, after that day, I (slowly!) started to understand how salespeople can be really, really good at a really, really hard job. I very much enjoy sales now and I think I have a lot more empathy for where my customers are coming from thanks to that very dark day.

* Not communicating enough with my team lead. This impacted my ratings. There will be places where you will be stuck early in your career. It's better to openly ask for help in such cases. This works even well if you are a star performer. Pratall effect is real.

* Applied wrong Cron job string for a mailer job to renew an IT asset. Instead of mailing at a specific time, mails went every second. A Senior exec(boss's boss) called and asked me to take it down. I was mortified for a moment since this was an unapproved use of company's resources. Thankfully nothing bad happened.

Any significant action or inaction early in a career can be considered a huge mistake years later with 20-20 hindsight.

And it actually depends more hugely on exactly particular goals which are always going to change over a career anyway.

Especially if you allow for this in advance, the very same actions or inactions of the past can turn out to be a great advantage in case an unforseen future comes along.

Where you can respond to a moving goalpost or even help place it in the path of your most applicable strengths, when you need it most.

You certainly won't be able to change those early career actions or inactions regardless.

Didn't start my own business sooner.

My biggest mistake... is not a technical mistake. It's a mistake about the career in its entirety :) The story is that I spent all my university years (and a couple of years after that, working in the IT industry) thinking that what I really wanted to do was being an CS academic. For a few personal reasons, I really inflated the idea. Then, finally, moved countries to start a PhD in one of the best universities in the UK, and... quit after not even 6 months. The mistake: idealising the academic lifestyle. I thought that being an academic was the only way to really work on something you love, being free to do it when and where you wanted, engaging with brilliant people. It turns out that two things are true: that you can find these things in many other professions; and that... often the reality is you won't find these in academia (of course, there are great exceptions). Moreover, a PhD – especially in the UK, and especially in computer science – is an really, really narrow endeavour. I wanted breadth on the side of depth, and a PhD (nor 90% of academic research) would ever be like that. I had entirely idealised a profession without looking at the reality of what it's like, and the reality wasn't a good match for what I wanted. It's taken me about 10 years to process and be happy with it, though :-)

I built our CI and tested failures and deployments. I never tested someone intentionally stopping CI while it was in progress. Two days after the team started using it, we realized we needed an immediate revert but the code was currently being built. So we just hit “stop” on the TC job. No big deal right? The current step was stopped, but it moved onto the next step like it passed. It deployed terribly broke things to production.

This is when I learned TC sent SIGKILL on a stop and not SIGTERM, which my scripts were expecting.

Deployed some code worked on by an intern without properly reviewing it. The changes weren't so much the issue, the problem was that they had migrated the project from SVN to Git but had neglected to check in the .htaccess file restricting access based on UNIX group membership. It took us some weeks to discover that everyone on the intranet now had access to the app.

I recall this particular intern used GUIs for everything and suspect their file manager wouldn't have displayed dot files by default.

Early in my career I was working at Cinematronics, a coin arcade game company. One of the developers came back from some meeting/conference with a glossy flyer for a startup. It had a line of people dressed as cowboys, astronauts, race car drivers, etc. It said something like, “We’re looking for rock star developers to help us create the future of video games. Join us.”

We thought it was cute, but none of us followed up on it. And that’s how I didn’t (try to) go to work for the startup Electronic Arts.

Before I understood Git merging strategies and so on, I accidentally introduced a ton of merge conflicts one night when I was trying to wrap up a bunch of UI things. My teammates were not happy, but I chose to spend all night resolving it manually. Now I have a better sense of git lol, still terminated later on tho.

Other than that, I still don't really know how to hold a programming job for longer than 6 months, so I'm sure there's a lot of mistakes I'm making.

My biggest mistake was while studying in university in 2004-05, i took three electives in AI, such as Neural Networks and Machine Learning. Even though I enjoyed the subjects and did well in them, I was too afraid to major in them and make a career out of it. I got scared by the math but also life took over and i probably didn't see myself having a career in AI. Now 15 years later looking back, it seems such a dumb mistake not pursuing those further.

I was working on a small webdev company. One day I had to update DNS records from X to Y because of Z (don't remember exact reasons) - turned out that my change broke setup for company e-mails (not ours, our clients) and they were offline for like half of the day until someone figured out what exactly happened.

Later it become a meme in that company, that every webdev need to break client's e-mails at least once, because it happened to other devs 2 or 3 times :)

Putting up with crap from all the peripheral people sucking the life out of creating great software. So many self-absorbed, clueless people trying to tell me what to do. If you are great at coding and getting software to work.. BELIEVE in yourself and fight for the code. Don't let social hierarchies dictate your art and it's form. And if you don't think code can be art then maybe do something else.

If you're not making an abundant number of _technical_ mistakes early in your career (like your examples), you're playing too safe.

If you're working at a place where you'll be punished or "get fired" for mistakes such as the ones you exemplified, and you have the chance (most of us are fortunate enough to have more plenty of options) - avoid that early career mistake and change jobs (-:

Staying with the first company too long.

Report a defect in a product that production management did not want to fix. I got kicked off the project and it took years to clear my name.

I am in my second company, I am here for 9yrs now. In the first company I was there for around 3.5yrs. Reason to leave was, I had nothing new to learn, I basically automated most my work, trained subordinates well enough to give me reports also trained them to review reports and send me one-liner like something needs attention or not. Learnt MS-SQL SERVER, SSIS AND SSAS and Cognos me originally being mainframe z/OS Db2 DBA. Lead SQL Server and Db2 team. Salary was avg but life was good, good managers, good place, location U.S Vermont, I am chennai, south india, it's summer throughout the year. Seeing snow was awesome.

I quit to learn new things. Now in this company I learnt and learning, made lots of automations but I always look back and feel why did I leave for that reason.

Like I have automated most my work, I have subordinates who report well, my lead DBA, managers are good, colleagues are good. I just didn't have patient to enjoy that.

In my first job as a software engineer I was working on an inventory management system for the University I attended. The original source for the data was a wacky Access database. We had a copy of the data imported into MySQL in production and it was not uncommon for me to try something, corrupt my local database, and need to restore it from backup.

When doing so I would typically run "TRUNCATE items;" on my local and repopulate it with the content from the not-yet-live production copy. This worked great until the afternoon where I was doing a demo for my boss in the office, realized my local datastore was in a bad state, and then got my tabs for "production" and "local" mixed up in my terminal. I truncated the entire dataset on production while my boss was standing behind me.

I got to learn a lot about how to export from Microsoft Access and import to MySQL that month. Lol.

Not asking what the promotion path of my first dev job would be. As it turns out, there wasn't one: I was hired to be a code monkey, and a year and three "annual" performance reviews later, I was still a code monkey, with no change in responsibilities.

Don't be shy about asking what the near future of a role is.

My biggest mistake was to discount and ignore the importance of management as a skill.

As a good technician, I moved up to being a junior officer in the Navy and completely missed the point that I was to work through the enlisted sailors, not join them.

I found myself staring East all night wondering why I was struggling. Suddenly, it dawned on me.

I got a call back from havok to interview for an internship during summer of my third year of college. I said no, because I'd just walked out of accepting a summer internship with a physics professor in my university. Never quite forgave myself for that one, I should have just bailed on the physics dept.

I worked at a consulting place for ten years that was packed with a bunch of wise veterans who were mentors for me. They also paid poorly and had no benefits. A pivotal place for me in my career but I should have left a half decade earlier.

And I wanted to work there so badly that I jumped on their first offer. The classic.

My biggest mistake was not investing enough in relationships - especially with peers. To anyone starting out now, this would be my number one point of encouragement: greet each day with love, invest in your relationships from the outset - perhaps moreso than you think is typical.

Aimed too low. If you are smart enough to be hirable in tech, you are smart enough to do so much more, and less clever people than you luck in to more success, so be luckier.

Also in the 90's, knocked west coast offline by null routing the /24 that contained peer router addresses. Broke DNS for a few thousand domains by corrupting named.db on our primary NS before going to lunch, editing the sendmail.cf on the primary mail server in production for an ISP without revision control. I worked for the kind of people who could debug a sendmail.cf cold, so they could afford to have someone as dumb as me around, but still, I meddled in the afairs of wizards.

Becoming too emotionally invested and involved in the welfare of the company where I worked for seven years. This had the opposite affect with my boss and management because I was making delusional organizational and engineering decisions with no authority to do so. Even though I thought my intentions were aligned with the future of the company, nothing could have been further from the truth.

My advice is keep things professional and even ruthless long into your career at a given company. Clock in and clock out and always take challenges impersonally. Be the impeccable toy model your boss wants you to be and nothing more.

I pretended to often that I had figured everything out and didn't need any help. Although this worked out ok, I would have surely learnt more if I had more often admitted that I was stuck and asked for some input.

Biggest mistake was suggesting parellelizatio n of test procedures in a satellite program saving multi-million dollars of test time then not claiming it as my own idea.

- The boss stole it and got all the upper-company accolades.

Based on the comments, this might be a slightly different POV on the topic, but not understanding the value of personal/professional networking and soft skills. Very early on in my career, I was less interested in the networking aspect, and more focused on (for lack of a better way of describing it) pure meritocracy - if I become more skilled, more opportunities will naturally become available. I eventually discovered how narrow of a view this is and sometimes wonder how life would've gone if I'd had a different mindset earlier in life.

Sofware unrelated: I was an underqualified "sales" associate handling an incoming call for an order, when I thought it would be better for the business to call the overdue account of the client into question. I ended up saying "If you don't pay your bill, then my boss doesn't get money, then he doesn't pay me and then I can't buy groceries for dinner." - only for my sales manager sitting next to me go completely wide-eyed in disbelief as he had to wrestle the phone off me and recover the phonecall!

Don't look for jobs, look for opportunities. Just because you like the work today doesn't mean you will continue to do so. If you can't grow and evolve...well, that's the worst thing ever.

Put another way, it's a relationship. The opportunity is relationship with your employer; a career is a relationship with yourself.

Don't get stuck in bad relationships.

To that point, when in doubt update your CV and look for work. When you eel helpless (i.e., you don't like your current work situation) looking for sonething else is empowering.

Don’t focus on being friends with anyone and just make the boss happy.

Stayed in Canada too long.

It had always been in the back of my mind to move to the US for work but I never did due to not being confident enough.

I realized in my mid-30's that I was approaching a "now or never" scenario and finally made the move to the Bay Area. I really wish I had done it right away at the start of my career rather than spending time at small companies working on small projects.

I know it's better late than never but I know I would have been so much further along in my career by now had I followed my instincts.

Not early, but: talking to the press without any media training.

I didn't listen to people who knew better.

Time and again I learned harsh lessons that shouted "Why didn't you listen? He/they/she said that would happen."

My mistake was talking about other job opportunities with my colleagues. Ended up my boss learned about it and talked with me saying that I was being ungrateful and thinking too highly of myself or something on that line. Well, I do not resent my boss or anybody. What I got out of it is to simply "shut up" and do the job or quit the job - which has been serving me well ever since.

Not pushing boundaries and (respectfully) questioning authority about why things were the way they were, being afraid of making mistakes.

Working in tiny companies rather than large one. Now large ones will say to me - you've messed around loads why should we take you?

It was my third year of my first job, I was alone working on the live database. I ran the following SQL command in SSMS:

DELETE FROM TABLE WHERE ID = something

And the table had a million records. Guess what!

In SSMS, the DELETE FROM TABLE was selected.

It took an hour to restore from backup, it stopped a lot of people from working, many new records was lost, they had to keep pile of papers to enter into syatem again.

Not following thru, on so many things.

Perseverance is everything.

1. Not networking. ...and I still don't even though I'm actually quite good at socializing.

2. Not trying to make money from day 1 for something slightly non-profit because we were afraid it would drive people away. I think it would have been more honest, closer to where we wanted to get and ultimately it could have funded us to continue our work.

I once worked for a startup where the founders had a very obvious bias towards hiring people with a certain skin colour. My mistake was mentioning it to HR. I was accused of racism, demoted, and forced to take cultural sensitivity training. That was the day I learned you can't trust HR no matter how friendly they are in person.

In a test project for new location services inside a mobile network, I was provisioning 1000 employees with new sim cards, and inevitably a few got mixed up. One of those was someone's secretary who ended up having a phone number of someone with high security clearance who deals with national security type stuff.

Does being born count as early in my career?

In the early 80s, assuming that programming was easy, and that there would soon be a surplus of programmers. My mom was teaching programming at a nearby community college, and her students were getting programming jobs after one year of instruction.

Still, I don't regret my career, and I get to do a lot of programming.

I would say, not letting go when I disagreed with some decision I knew was wrong. Younger me would tend to tenaciously fight those, to my detrement. You end up getting a reputation for being argumentative or hard to work with. Later I learned waiting things out and more subtle ways to affect change.

Undervaluing myself and not having my personal life in check. Spent a lot of time juggling what was essentially dead end volunteer work with trying to sort out whatever drama my ex had constructed that week.

Not quite what you're asking, so sorry about that, but it's my answer to the general question

Not believing in myself, having low standards, not being picky enough and ignoring immoral actions and dumb decisions made by CEOs. Those of us who come from poverty often have low self-esteem, it's something that needs to be worked on constantly, like a rotting codebase.

“Upgrade these systems for a customer”, they said.

“They have backups”, they said.

I encourage the reader to guess what they said next :)

Turning down a promotion to VP early in my career, now I’m in my mid 50’s and no one truly understands why I didn’t. Personally I didn’t want to ascend into mediocrity like most VP’s and above. Now I’m having trouble with age bias as a Director or Senior Director.

Ho-hum.

I used to forget my note to self TODO messages and accidentally sent “oh fuck fUuCcccccck you stupid idiot fix this you suck at your job…. Blah blah blah “ In a deploy that made it to production, the actual copy was much more offensive

My company gave me a little too much responsibility as a junior data scientist... I pushed a model to production without doing due diligence, and ended up spending an extra $60k in about 45 minutes before it was discovered and pulled.

Turned down an acquihire offer at age 21. It was my first "startup" (me, cofounder, some code, few never ending trails, 0$ income). It was a 1m$ for each of us spread over 4 years, in addition to bigcorp salary and benefits.

i was too focused on the intellectual side of technical work and didn't understand i was in the business of selling my labour, the importance of exploring and cultivating different opportunities, and then negotiating a good deal.

Staying in one place for far too long.

You learn and earn more by jumping ship after a year or two.

I encouraged my employer to get on board with the personal-data-for-access trend.

My biggest early career mistake was starting a career too early (18). In my case (and I’m tempted to generalize it), having good knowledge of the self prior to working is critical for long term outcomes.

Not taking investing seriously or making a budget when I had my huge wins

I put up an "Under Construction" page for an insurance claims processing site at my first internship while I worked on changes to something or other.

In production.

That didn't stay up for very long :)

I once broke an NDA by posting to a forum about software I was evaluating from a big company. Super not cool. I survived but had a good beat down from the CTO.

Joining a big company and not leaving on time. I spent 15 years there but the last 3-5 were looking for something else. Finally I just quitted.

Fortunately the repercussions were minor, but the mistake is still a huge facepalm. Storing monetary values in the database as simple floats.

Not focusing on single topic and being an expert on it at my job but mixing personal development and professional career.

My biggest mistake is that I was working in security but left it for a different path. I could have been a hero!

Stayed too long at my first job.

I should have stayed in the Bay Area and followed up on WhatsApp and Instagram.

I joined the Army. That's seven weeks of my life I'll never get back.

Qualifying as a lawyer when what I enjoyed was building things.

Trying to work for someone else.

It turns out that I just can't work on software that other people built. I have too strong of opinions, which could also be considered a mistake.

I'm still early in my career, so I haven't made many.

I moved to LV, NV.

Not leaving my first job four years earlier.

Spending time on non-technical tasks

Not asking for help, generally.

Not signing up for ESPP. Doh!

going to the wrong university.

Mistakes?

(1) By accident, I had a relatively good career going around DC in applied math and computing for US national security. I thought it would help my career to know more math so got a high quality Ph.D. in applied math. I WAS then better qualified, but I also had broken my career continuity. My brother saw that early on: "After your four years in graduate school, you will be four years behind in your career."

And, I didn't realize that the opportunities in DC were unique or nearly so. I would, could, should have (A) not assumed my career would work away from DC and (B) stayed in DC.

Lesson: If you have a good career going in DC, NYC, Silicon Valley, wherever, don't assume without good evidence that that career will also work in another location.

(2) Near the end of my Ph.D. work, I had a part-time job and did some good things. Then occasionally a person never seen before was in the office for a few hours one or two days a week and wanted to chat with me about whatever, even sports. Eventually he got my opinion on what the US did in Viet Nam. In retrospect I was being recruited for some high end highly secure slot but violated a rule Mom gave me -- never talk about politics, sex, or religion. I had talked about politics. Don't do that. So, being frank and honest about Viet Nam cost me a good career step.

(3) Dad's idea about a career was to get a good education and, then, a good job based on that education. Eventually I concluded that, nope, instead, with or without a good education, it is from important to crucial to own a business and to make it successful, and early in a career near the top of the TODO list is to find a way to own and run a successful business.

(4) I didn't understand an important point about career dynamics: (A) It is tempting to guess that academics is good preparation, maybe the best, for a non-academic career. (B) Instead, for a successful non-academic career, it's important to ride the waves of the hot topics, and, bluntly, academics is largely out of touch with what the hot topics are. (C) While some academics can help, possibly a lot, there is a special way to know what the hot topics are in a non-academic career -- see what work and topics people are getting hired for.

Net, be reluctant to let academics tell you what will be important in a non-academic career and, instead, let a non-academic career tell you what topics are important for you in academics. And if have a good ugrad education, then pursue those topics while on the job by independent study evenings and weekends, maybe partly on the job -- to pursue those topics, don't leave the job to become a full time student.

E.g., when I was in my Ph.D. program, there was a prof, soon famous, who apparently had been hired as a consultant to work on a topic, call it, X. Well topic X was in practical computing, a bit tricky, not at all a topic in academics, and from my non-academic work a topic I knew well. With resentment the prof asked me: "I suppose you know X?" I had a one word answer: "Sure". Really it was a collection of topics such as X that had my career going well, e.g., annual salary six times the cost of a new high end Camaro. For that summer job working on topic X, the prof was about to have a tough time!

(5) One possibly good career direction is to get a job in a startup in its early days and get stock. For the stock, before joining (A) get the stock deal in WRITING, (B) study the details of the stock deal (e.g., vesting), and (C) have the deal reviewed by an appropriate lawyer. Handshake deal? Don't do that.

(6) Applied math and, usually, computing work or don't independent of human emotions. People, however, commonly are driven more by their emotions than what is true in math or computing. It is crucial, then, to pay close attention to the emotions of people.

As a special case, one way to get people to hate you and work against you is to present some work in math or computing that (A) has power important for the organization, (B) is understood only by you, and (C) looks rock solidly correct and, thus, not easily ignored. Then the people who hate you maybe cannot find fault with your work but might be able to arrange to get you fired.

Part of one way to get you fired is gossip -- be aware that you may have to defend yourself proactively, guess what you are secretly accused of and then defend yourself against the accusations.

More generally, whenever you start to be especially successful, you will attract attacks like some piles attract flies.

(7) There is discrimination in the US. Not often mentioned is that there are some cases of severe discrimination in the US against native born Christian males of European descent. So, it can be important to realize that fact.

(8) Try to keep confidential and not to report on work in progress: If your work looks good, your enemies will try to kill off your work before it starts to show its power or arrange to take credit.

(9) There can be corruption, e.g., people getting quite secret financial kickbacks. So, you can get a bitter enemy if, even without realizing it, you threaten their corrupt money. So, at least try to guess who might be corrupt and how, and then try to avoid that person or their source of corruption.

Of course, if there is someone corrupt in the part of the organization chart you manage, you will likely want to get this person moved out. Of course if the corrupt person has some close, say, family, connection with, say, a member of your BoD, then you have to be careful!

Point: Be aware that corruption exists.

I don't know if it's huge, but I should have put more in crypto and perhaps should have joined a company pre-IPO. I think at the IPO price I would have netted a net worth of $1m+ from option exercise for just about 2 years of work. Of course, now they've halved in value post lockup so I don't feel too bad.

It's fascinating how many comments are of the form "stayed too long with an employer before finally leaving".

Take heed.

Staying too long in my first job

Not pushing for promotions/more responsibilities

Getting attached to my original team.

Thinking other people had my career as their concerns

Tolerating some bosses disrespect

Attaching my visa to my job <- Modern slavery

Moved to Canada instead of moving to the US.

Not having a lawyer review my ESOP.

Taking a year break in 2014.

I lost potential to earn millions from continuity of my career. It was the early days of many startups

I also discovered I like coding and don't really enjoy traveling.

Traveling is romanticized too much in our culture.