Are you on a Linux distro? The reason that this happens is because Firefox in Linux uses many internal libraries, some that are incompatible from one (even mino

Are you on a Linux distro? The reason that this happens is because Firefox in Linux uses many internal libraries, some that are incompatible from one (even minor) version to the next due to the tight coupling of some of the libraries. Combine that with distro-managed updates, and the result is the restart dialog. Updates on Windows and macOS are different though, they are controlled by Firefox and you can delay updates even when the update is downloaded (Windows users might even see the loading bar associated with the update).