How can this happen when Linux package managers don't auto-update (without help)? I mean if you don't want Firefox updated while you are using it you just just don't update it. If your distro has some sort of auto-update by default (do any do this?, I thought available update notifications was the standard) then disable it and get control of that back. Auto-updating packages is an anti-pattern (ie. bad).

It can also happen if you have two copies of 'stock' Firefox running (with different profiles) and one of them runs the update.

Probably. Never seen anything like that on Windows or macOS.

I get 'Firefox needs to restart' all the time on MacOS.

Right, but it doesn't auto-update and kill your session.

Yeah it does. It might be possible to disable it though but as far as I'm aware it's enabled by default.

No, it prompts first.

It is a preference you can set.

It is a preference. I’m not sure what the default is, but the recommended is to have it done without prompting.

Happens on Mac all the time.

… Firefox on my work macOS is presently has an emblem on the hamburger menu, and if you open the menu: "Update available — restart now". I've been delaying for days? weeks? at this point.

Clicking it causes the browser to disappear for ~20 seconds, +10s for the UI to become available.

Happens on Windows

Never once in my experience, and I haven't configured it otherwise.

Whenever firefox on Windows at work starts to act flaky (won't let me open a new tab, stutters, locks up for a while) it's probably going to update when I close it down in frustration and open it again.

I have (macOS).

… it doesn't, and I've just run `pacman -S` to check. (& it didn't.)

(It does cause some tabs to message that a browser restart is required. Even so … this is really the first I hit this, as I'm usually doing updates when it is opportunistic to do so, such as right before a reboot (so any kernel updates happen).)