Just finished testing and this one is working!
You can consider this one solved.
However, if you need some more information on this, let me know.
Thank you for the support.
I recently had a sync error with a contact that had a UID: k4T611X7D4\\r
Only this contact had a sync problem.
It was made by OwnCloud (PRODID:-//ownCloud//NONSGML Contacts 0.3.0.18//EN).
I fixed this by simply removing the "\\r " from the UID of the contact in the contacts.vcf that radicale was serving the contact from.
The log shows that davdroid looked for the contact at a strange location:
2017-04-18 12:49:09 3 [dav4android.DavResource] Received <response> for https://server.com/username/contacts.vcf/username/contacts.vcf/k4T611X7D4//r
I expect this url is supposed to be https://server.com/username/contacts.vcf/<UID>, but there is an extra /username/contacts.vcf/.
Here’s the log complete with a traceback.
Similar: Avoid using @ in UIDs?
davdroid version 1.5.03-ose