@j-ed You were right! The issue was on the Nextcloud side - apparently some of the metadata of my contacts had been switched around. I fixed that and now my problem is solved. Thanks for the quick help.
Davdroid & nextcloud some events and contacts could not be synchronized
first let me say that everything worked perfect to some days ago. No update of server, nothing has been changed in configuration on the server, some updates of davdroid has been done, but the problem has not start occurred after davdroid update. The strangest thing is that in some day something has happened and now some of the events and contacts are not synchronized between server and davdroid.
I don’t see any issue in the logs:
Content of Nextcloud-G6HVB9G284F8N9C2L65QN.ics file:
after several synchronizations, the problematic (above) event has been copied but another one not… I don’t know what is happening…
another problematic events:
at.bitfire.dav4android.exception.DavException: Received CalDAV GET response without ETag for https://SERVER/remote.php/dav/calendars/USER/personal/Nextcloud-G6HVB9G284F8N9C2L65QN.ics
At least this error is a server-side problem. Please contact your server support. You may also search the forums for “ETag”, there are some related threads (where ETag has been disabled in the Web server, but it’s required for CalDAV/CardDAV).
after update of nextcloud, the problem has been solved.
One remark, after each update of nextcloud I have to apply the hint from
maybe you should add this to the FAQ or Configuration section.
I have encounter this problem once again, I have reported it to nextcloud community (https://github.com/nextcloud/server/issues/6657)