* I use CalendarServer

* I have in-house custom client

* I was trying to create and update the same event multiple times with different dates.

* Then, I started getting 412 error back from server on PUT request.

* Subsequent, REPORT query does not return any ETAGS

How can I find out what is wrong with this event.

63.83.229.146 - - [23/Jul/2018:02:02:09 +0000] "PUT /calendars/users/user1/calendar/a2ed0ec5-cdae-4b71-9ea7-be45634c27cb.ics HTTP/1.1" 401 141 "-" "Jakarta Commons-HttpClient/3.1" i=1 or=1 t=14.4

63.83.229.146 - user1[23/Jul/2018:02:02:09 +0000] "PUT /calendars/users/user1/calendar/a2ed0ec5-cdae-4b71-9ea7-be45634c27cb.ics HTTP/1.1" 412 225 "-" "Jakarta Commons-HttpClient/3.1" i=1 or=1 t=12.1

63.83.229.146 - - [23/Jul/2018:02:02:10 +0000] "REPORT(CalDAV:calendar-query) /calendars/users/user1/calendar/ HTTP/1.1" 401 141 "-" "Jakarta Commons-HttpClient/3.1" i=1 or=1 t=9.9

63.83.229.146 - user1[23/Jul/2018:02:02:10 +0000] "REPORT(CalDAV:calendar-query) /calendars/users/user1/calendar/ HTTP/1.1" 207 66 "-" "Jakarta Commons-HttpClient/3.1" i=1 or=1 t=17.4 responses=0

Can you please help me resolve this?