There are a number of upstream bug reports mentioning MODIFICATION_FAILED (https://bugzilla.mozilla.org/buglist.cgi?quicksearch=MODIFICATION_FAILED), but at a quick glance nothing that matches the problem you're describing, so I'd suggest filing an upstream bug, and sharing the link to it here.
Also, there are many calendar-related fixes in the new stable series (91), so it could very well be that the problem is fixed there. As of 5 hours ago, Ubuntu 21.10 has thunderbird 1:91.1.1+build2-0ubuntu1, so you should be able to update and test that new version (feedback welcome in the form of bug reports, by the way!). -- You received this bug notification because you are a member of Ubuntu Bugs, which is subscribed to Ubuntu. https://bugs.launchpad.net/bugs/1945200 Title: Updates to Google Calender succeed but produce MODIFICATION_FAILED error To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/thunderbird/+bug/1945200/+subscriptions -- ubuntu-bugs mailing list [email protected] https://lists.ubuntu.com/mailman/listinfo/ubuntu-bugs
