Hi, there is definitely a migration script, so there must be something else that went wrong. OneTab storage is handled by Firefox, and is stored in Firefox's internal databases. For some reason, Firefox has wiped this storage area. Do you remember recently being asked if you want to "Refresh Firefox"? This is a prompt shown to you when you upgrade to a new Firefox version (there is a new Firefox version released every month). The other possibility is if you had a browser or PC crash, which caused a disk corruption in the Firefox internal storage areas. Firefox would then wipe clean the affected storage area.