CoreDAVHTTPStatusErrorDomain 404 - Contact Sync fails with Deutsche Telekom Cloud

Dear Community,

I used OS X 10.8 over 2 years with with a sync-plus software of Deutsche Telekom. I was able to sync the contacts which are stored in their cloud to sync to the local contacts app. Fine.

I recently updated my MacBook pro to 10.10.3 and today to 10.10.4.

Since I did the update to 10.10.3 I was forced to update sync-plus as well.

Sync-Plus creates an additional account entry "Telekom Cloud Kontakte". I can see this under contacts accounts.

But I'm getting an error message "Der Vorgang konnte nicht abgeschlossen werden. (CoreDAVHTTPStatusErrorDomain-Fehler 404.)"

Deutsche Telekom support try to follow this error message, but can't solve the issue. Other users reports no issue with this software. It was tested and approved with OS X 10.10.

I uninstalled ans reinstalled the sync-plus software again with the same result.

There might be an issue due to the update procedure or the deinstallation is not able to remove all fragments.

It seems like an error in the handling between the sync-software and OS X.

Any ideas what I can try to solve this issue?

Best Regards

Dirk