Did your Addons migrated ? How did you migrated your profile? *Copy the entire content from the older profile to the new profile ? ________________________________________________________________________________ If you can restore the entire profile, Profile Folder location */Library/Thunderbird/Profile/xxx.default/ Or try the which file you need to restore */Library/Thunderbird/xxx.default/calendar-data/local.sqlite */Library/Thunderbird/xxx.default/prefs.js