Hello, Thunderbird got updated to 78.12.0 by Mozilla Maintenance Service this morning and I believe Firefox got uninstalled by accident during the process. The reason I think it got deleted by MMS is because in `C:\Program Files\Mozilla Firefox` I could see a single file named `tobedeleted` and when I read the log located at `C:\Program Files (x86)\Mozilla Maintenance Service\UpdateLogs`, the last two lines were : NS_main: unable to remove directory: tobedeleted, err: 41 NS_main: directory will be removed on OS reboot: tobedeleted Luckily my `%APPDATA%\Mozilla\Firefox\Profiles` were not affected by this issue and I managed to recover my data by reinstalling Firefox. Best regards, Tolga Taluy