Thanks for the fast reply. Now it functions, in this spezial entry (line 1787) the timestamp was not set in the database. Also the link ist very useful.
But I had a second problem, where there is the same error message, but I don’t find a false entry and all timestamps seems to be right.
Perhaps you can help me one’s more please, even I think the problem is not ICSx internal: [https://lfv.sybos.net/sybServices/webcal/index.php?token=59cba24f5021c](link url)