Also here: Recurring events (such as birthdays) not working at all, regardless if you enter them via outlook365-calendar or OneCalendar on your mobile phone. Renders this plugin useless. Tried re-installing and also different mobile calendar apps. Recurring events not only returning an error, but the event also duplicates itself every hour, ending up having dozens (hundreds if you don't stop them) of the same entries in a day. Can't even delete these events using the client, need to log-in to webmail...
CalDav '500' ('Internal Server Error') synchronizing with EDIS CalDav Server