I have my Mac and thunderbird set to auto-update, so I am not sure where the culprit lies. But my system did a Mac update and a Thunderbird update both recently. I'm now on Sonoma 14.3.1 and Thunderbird 15.8.1. When I started thunderbird it spun for 10 minutes. I thought it was locked up initially, did it again and even tried starting in safe mode. But after about 10 minutes, it eventually stopped. Problem was all my calendars won't display. I can add or remove either. The interface is barely responsive, and it crashes after a few minutes. I started Thunderbird from the command line to see if I could monitor the errors. I get about 100 of the following: 2024-03-10 14:06:22.361 thunderbird-bin[17189:518538] Rethrowing (from nts_ValueForProperty:) NSInternalInconsistencyException: Unhandled error (NSCocoaErrorDomain, 134092) occurred during faulting and was thrown: Error Domain=NSCocoaErrorDomain Code=134092 "(null)" CoreData: error: Unhandled error occurred during faulting: Error Domain=NSCocoaErrorDomain Code=134092 "(null)" ({ }) Anyone having similar errors, or any ideas on a fix? Thanks, Roberto