Running 102.3.1 on Windows 10 (20H2). Not sure previous version prior to update to 102. Usually on a copr VPN, which prevents more automatic updates. I seem to recall it was at least 89, but may have been in the 90s. Events are (mostly) not displayed in Today Pane or in main calendar grid. They (mostly) do display in the Events List (above the grid). If I add a new event, it will appear in the Today Pane, for a while, but some time later has disappeared. I found [[Thunderbird calendar data lost after upgrade to 91|this article]] and tried the solution, but I don't have any entries with NULL ID. I opened the Error Console and find >80 messages indicating an error for "zone is null": ''Calendar: Exception { name: "NS_ERROR_XPC_JAVASCRIPT_ERROR_WITH_DETAILS", message: "[JavaScript Error: \"zone is null\" {file: \"resource:///modules/calendar/Ical.jsm\" line: 5520}]'[JavaScript Error: \"zone is null\" {file: \"resource:///modules/calendar/Ical.jsm\" line: 5520}]' when calling method: [calIDateTime::getInTimezone]", result: 2153185313, filename: "resource:///modules/calendar/calStorageHelpers.jsm", lineNumber: 189, columnNumber: 0, data: XPCWrappedNative_NoHelper, stack: "newDateTime@resource:///modules/calendar/calStorageHelpers.jsm:189:19\ngetEventFromRow@resource:///modules/calendar/CalStorageItemModel.jsm:653:24\ngetEventFromRow@resource:///modules/calendar/CalStorageCachedItemModel.jsm:148:24\ngetRecurringEventAndFlagMaps/<@resource:///modules/calendar/CalStorageItemModel.jsm:426:29\nhandleResultInner@resource:///modules/calendar/CalStorageDatabase.jsm:176:21\nhandleResult@resource:///modules/calendar/CalStorageDatabase.jsm:170:41\n", location: XPCWrappedNative_NoHelper } CalStorageDatabase.jsm:190'' Database reveals 38 events with "floating" event_start_tz and event_end_tz, and another 255 with those stored as tz definitions (BEGIN:VTIMEZONE.....). The balance (1339 events) have the fields set to "known" zones such as "America/Chicago". I can't find in the Error Console any pointer to specific entries in the database. Expanding the error in console seems to me to further describe the code, rather than any info about the data. There are a few other errors in Console as well, but I hope that a) someone can provide a solution to the general problem; or b) a solution to the described errors will provide me some tools to figure out the rest. Thanks in advance.