Events can't be moved from one calendar to another

[ajaxovic]

If you wan to move event in webgui from one calendar to another, system report Could not update event: Unexpected CalDAV error.. It took me for a while to find solution for that, But I failed.

One note, I found, that Thunderbird makes 11 requests to dav server during calendar edit (create same event in new calendar / delete old event in old calendar / lot of checks between that). But Roundcube driver makes only three requests. Create new and some checks. Maybe, you know what to do with that...