I posted following problem to the OutlookCalDavSnchronizer-Community because I thought that the problem were there. But apparently it is not:
I sync a Task with a start and end date via OutlookCalDavSnchronizer to my Baikal-Server. Afterwards Davdriod would like to update the Task on my Android Handy but it fails with the following error:
If you need help too better reproduce the problem I can give you access with a temporary user account to my server. Then you can sync at task which was already uploaded by OutlookCalDavSnchronizer. Please send me a PN.