When Firefox is running and you forget to close the web browser windows before initiating the system reboot, the newer versions of Firefox might automatically launch after the system has booted up. This works in the newer versions of the Windows 10 operating system. The usefulness of this feature is that if Windows automatic updates forces you to restart your PC while you were in the middle of using Firefox web browser and the browser was not shutdown properly, then it will be launched automatically at next boot and you can resume whatever you were doing in your PC.
But if you do not like this feature, then you can follow these steps to disable it:
- In Firefox browser’s address bar, type about:config and press Enter.
- Dismiss the warning by clicking on I accept the risk button.
- Search for a setting named toolkit.winRegisterApplicationRestart and change its value to false.
- Search for the setting named browser.sessionstore.resuming_after_os_restart and change it to false.
- Now if your Firefox is shutdown inappropriately due to system reboot, it won’t relaunch at the next boot.
This feature from Mozilla Firefox browser is meant only for the situations where the browser was shutdown by the operating system when the system was being shutdown. These settings will have no effect if the browser was shutdown because you terminated the processes associated with Firefox (for example, “firefox.exe”) inappropriately through Task Manager or using the “taskkill” command.
Furthermore, this feature seems to work only on the Windows 10 versions 1809 and above. It won’t have any effect on other operating systems. As a matter of fact, we could make it work it with Firefox browser version 64 (64-bit) running on Windows 10 (64-bit) version 1809. In any case, you can avoid Firefox from relaunching after rebooting Windows just by closing all the browser windows yourself.