Firefox updated from 131 to 132 and deleted all bookmarks, history and emptied the bookmarkbackups folder. It displays a message that a Firefox file is open by another application and that some security software can cause this problem. According to Task Manager there are no other applications running, nor is security software running. (I turned off Windows Defender and rebooted.) The problem persists. If I can't recover the 80 or so complex bookmarks, I'll have to try MS Edge browser. I'm sure that months of history is not recoverable and is lost forever. Was this software quality tested prior to distribution? If so, it wasn't very thorough. Why does Firefox delete files and folders during an update? It would be better to make a backup copies prior to unleashing a destructive update on unsuspecting users. Before you ask, no I don't create full backups because a) my laptop is used 12 x 7 weekly, b) a 4TB SSD full backup takes days, not hours depending on the destination and c) a 4TB SSD differential backup takes more than a day. I've tried both and they are not practical.