semi-old Firefox/Chrome can't update itslf, requires full reinstal, why?

I'm guessing there are some cryptographic keys included in the installation that requires updating once every N days, and if it doesn't, it's unable to validate new updates somehow.

"Evergreen" when it comes to browsers just means that they try to update themselves rather than letting the OS handle the process, it doesn't mean it's always successful :)

On Windows it isn't possible to remove or rename files and directories that are being used. In order to handle this, you typically have to run some sort of helper application outside of the installation directory. This renames the existing installation directory to a new directory with ".tmp" (often, not always, but this is my guess). If that rename operation fails in the middle of the operation because a file being opened, either by another process or sometimes by an add-on, then the background update fails.

On Mac and Linux it's less complicated which is why they never get the "download the new version" prompt, but Chrome and Firefox have evolved systems for managing how these silent updates work. On Chrome the update button you talk talking about means you haven't closed the browser in awhile. If you see green that means an update has been available for 2 days, orange – 4 days and red – 7 or more days.

My guess is that you are encountering a situation in which the Chrome background helper can't successfully run the update process and then asks you to download the whole thing again so they don't need to rely on the updater and can just move your user files over.

It might be that the browser onky downloads deltas to install and that after a certain point, those deltas either can't be computed or are large enough that a new download is better.

The connection to the update server must be secured, but it might not be using SSL the way connections to websites normally do. Perhaps the local install has not been updated in a while, so neither have the details about the server certificate. Then the local install might not accept the update server's certificate because the expected details don't match.

I have occasionally seen this type of construction when doing integrations.

A month or two old, and it couldn't update? This is surprising.

I just yesterday stumbled upon somebody's forgotten Firefox v43, and it upgraded itself to latest. It took three relaunches:

1. Peeked in the About box when the second site I tried to load glitched visibly. 2. Let it upgraded itself to v50-something. 3. Site still broken. 4. About box again, to see if it really updated… yep, but another update already downloaded. 5. Let it upgrade again (didn't note the version). 6. Site slightly less broken. 7. Back to the About box, upgrade a third time. 8. Site fully functional, but checked the About box again to be sure… 9. Up-to-date.

Edit: Just checked; user is now on v116.0.2

Not near enough details to answer this question.

What OS?

What version of chrome were you on when it asked you to install manually? (What version was the latest?)

Do you have your PC locked down in any interesting way that may cause problems with the installer?

Do you have the exact wording of the error message? (If you know th is exact wording, you could likely search the code base to find the message)

I've seen Firefox say it will wipe my profile because it was too long since I used it. But never had update issues.

To auto-update, Chrome needs to be restarted. If you never quit Chrome, it will never update. Could this be the issue?

I received that message and proceeded with auto update, got the latest version and message gone