CalDAV sync fails after upgrade to v29

resolved Nextcloud upgrade Reported 2026-02-01 Verified 2026-02-28

Calendar sync via CalDAV stops working after upgrading to Nextcloud 29. Clients report authentication errors.

Error Messages

401 UnauthorizedCalDAV sync failed

Resolutions (1)

medium confidence 8 verified

Clear the CalDAV cache and regenerate app tokens:

docker exec -u www-data nextcloud php occ dav:sync-birthday-calendar
docker exec -u www-data nextcloud php occ maintenance:repair

Users may need to re-add their calendar accounts in clients.

Verified by 8 users, v29-specific Added 2026-02-05

Applies to: 29.0 on docker