Thanks for the information and update! Great that you found it out.
Sorry for the inconvenience. Now we know that no_script prevents the usage of the forum. We’ll have a look at it.
On Roundcube I created a second calendar, which I deleted a while after that.
I synced both with DAVdroid to my Android phone and to my calendar on OSX.
When I deleted one calendar it was also gone on OSX but DAVdroid still tried to sync it.
Duplicate of #243. At the moment, DAVdroid doesn’t check for deleted or new collections but synchronizes the ones set up.