[Bug] Contacts not saved, Etag mistmatch

As I noticed, only the first edit in a contact is correctly saved. more changes throws xhr error “412 Precondition failed” with response:

<?xml version="1.0" encoding="utf-8"?>
   <d:error xmlns:d="DAV:" xmlns:s="http://sabredav.org/ns">
  <s:message>An If-Match header was specified, but none of the specified the ETags matched.</s:message>

I also got problems with davdroid which got sync problems caused of missing etags …
I think thats somehow a problem of nextcloud or the contact app?!

Can you report this on the bugtracker?

This is a duplicate, see https://github.com/nextcloud/contacts/issues/257