Firefox: notify me before update

I'm using Firefox 96.0 on Kubuntu (96.0+build2-0ubuntu0.21.10.1)

Sometimes, firefox updates in the background and then comes up with a message "Sorry. We just need to do one small thing to keep going.". I then can no longer do anything at all in Firefox until I restart - not open any new tabs nor use links in current tabs. This has cost me money as I have had this occur once while booking train tickets - after restart the ticket was no longer available at the offered price.

In settings, there is no option to warn about updates but wait with installing them after the update: under Firefox settings/General/Firefox Updates I see

Keep Firefox up to date for the best performance, stability, and security.
Version 96.0 (64-bit) What’s new
Mozilla Firefox for Ubuntu
Canonical - 1.0

Without any option to change anything. Whenever I google I see many hints how to disable updates for 7x-version numbers, and many people asking to disable updates altogether, which is not what I want.

Is there a way to let firefox warn me (and this is ok to really nag) to install updates ASAP but lets me decide when?

This answer is about turning off automatic updates. It does not notify you before the update.

Replace the snap version of firefox with the apt version. It would only update when you update the rest of the packages.

sudo snap remove firefox
sudo apt install firefox

Make sure to turn off automatic updates in the Software & Updates settings.

However, make sure to manually apply updates in a regular basis.

If you go to about:config in the address bar and then state that you will be careful, you can set some update settings that should help you.

In the search box after going to about:config type in app.update and set the one for app.update.auto to false, then lower set the app.update.notifyduringdownload to true so that you know when it is going to update.

Hope this helps!

Firefox upgdates come from the Ubuntu security repository and so are handled by unattended-upgrades. You really shouldn't delay these updates because they typically address critical security issues (see https://ubuntu.com/security/notices?order=newest&release=focal&details=firefox).

As to why Firefox exhibits this behavior, see https://bugzilla.mozilla.org/show_bug.cgi?id=1492023.

That said, you could change this behavior by doing one of the following:

Option 1: Install unattended upgrades only at shutdown:

In the file /etc/apt/apt.conf.d/50unattended-upgrades, uncomment and change this line:

//Unattended-Upgrade::InstallOnShutdown "false";

To this:

Unattended-Upgrade::InstallOnShutdown "true";

Then use the command line to add a configuration snippet for logind to allow longer delays during shutdown so packages have time to install:

sudo mkdir /etc/systemd/logind.conf.d
echo "InhibitDelayMaxSec=3600" | sudo tee /etc/systemd/logind.conf.d/00-InhibitDelayMaxSec

Option 2: Block unattended upgrades of Firefox:

This will block unattended upgrades of Firefox packages, so you will have to remember to manually run sudo apt upgrade firefox somewhat frequently.

In the file /etc/apt/apt.conf.d/50unattended-upgrades, add "firefox"; to the Unattended-Upgrade::Package-Blacklist section by changing this:

// Python regular expressions, matching packages to exclude from upgrading
Unattended-Upgrade::Package-Blacklist {
    // The following matches all packages starting with linux-
//  "linux-";

To this:

// Python regular expressions, matching packages to exclude from upgrading
Unattended-Upgrade::Package-Blacklist {
    "firefox";
    // The following matches all packages starting with linux-
//  "linux-";

There is a check box in Settings - General Tab to tell Firefox to stop auto update See this:

Update:

The answer by @Terrance defines another way of disabling update by modifying config variables. There is still another way of defining config variable to enable/stop app update or other things: by defining enterprise policies. The steps are outlined below.

1. Open Firefox and type about:policies in the address bar. Press the enter key.
2. A window will open which will list policies already defined.
3. Click the "Documentation" Tab on the left and you will see a long list of config variable you can define as policy in Firefox.
4. Close Firefox and create a folder distribution under Firefox directory.
5. Create a file policies.json inside the 'distribution' folder just created. Refer Documentation tab for name of variables as in step 3.
6. Edit the file policies.json and specify config variables like this.

{
 "policies": {
   "DisableAppUpdate": true,
   "DisableFirefoxAccounts": false,
   "DisableFirefoxStudies": true,
   "DisablePocket": true,
   "DisableTelemetry": true,
   "DontCheckDefaultBrowser": true,
   "SearchBar": "separate"
   }
}

7. Save the file and restart firefox.
8. Check the active policies by following step 1.

You should see something like this.

Running Firefox 64bit ver.108, and for quite awhile the setings for auto update has been 'missing'. If you want to still get updates, just not automatically (asks you instead of just interrupting and forcing update at inopportune times...), then try this:

The way I was able to 'disable' the auto firefox update (still downloads, just doesn't interrupt you and install while you sit there helpless) was: open settings - type 'about:config' then type 'app.update.auto' and change the setting to 'false' (see below from documentation)

AppAutoUpdate

Enable or disable automatic application update.

If set to true, application updates are installed without user approval within Firefox. The operating system might still require approval.

If set to false, application updates are downloaded but the user can choose when to install the update.

If you have disabled updates via DisableAppUpdate, this policy has no effect. Compatibility: Firefox 75, Firefox ESR 68.7 CCK2 Equivalent: N/A Preferences Affected: app.update.auto

So, also don't forget to type 'DisableAppUpdate' and change it to 'false' also!

MEANWHILE - be careful when using this 'about:config' as it can really mess things up if you are not VERY, VERY careful!!!

...for good measure, edit the /etc/firefox/policies/policies.json (and in any edit the /etc/firefox/distribution/policies.json) and delete the stuff there and instead add:

{
  "policies": {
    "AppAutoUpdate": false, 
    "DisableAppUpdate": false
  }
}