Although there is no debug info, it seems that Nextcloud returns an error when DAVx5 requests the events/contacts. Is there any indication that this could be a DAVx5 problem?
After the update to DavDroid 1.x I can no longer sync to my caldav server (owncloud 7.0.4 on Debian Jessie).
Each attempt at synchronizing fails with a traceback, which DavDroid reports in the notification area as an error “Server error while listing remote entries”. Full debug info are available at http://paste.debian.net/423154/.
As you can see, the server returns “500 Internal Server error”. This indicates a server problem.
A possible reason could be that since DAVdroid 1.0, DAVdroid queries only events in the future and the last 90 days by default. You can try Account settings / Limit past time events / Set value to blank (""). Then
<CAL:time-range start="20160101T191039Z" /> won’t be set in the request, and maybe your server can handle it then again. (See also OwnCloud “This recurrence rule does not generate any valid instances” for this topic.)
However, this remains a server problem and I highly recommend to fix it. The new feature of querying only a limited time range into the past increases performance and scaling ability.
Thanks rfc2822, I confirm that changing the range setting to the empty string does work around the issue.
FWIW, as a mere user, I cannot really fix the server side issue. I can report the bug report upstream to the owncloud developers. But the fact remains that there is something very basic (synchronization) that used to work in previous davdroid release, and that no longer works with recent releases — tagged as 1.0 nonetheless.
So while you’re absolutely right in saying it’s owncloud’s problem rather than davdroid’s, you might very well lose users over this. So if there is a way you can by default work around this issue, it might be in the best interest of davdroid users to do so.
With many thanks for this wonderful piece of Free Software that you maintain for all of us.