It’s at this line:
09-01 22:40:09.882 E/davdroid.DavSyncAdapter(7327): at at.bitfire.davdroid.resource.LocalCalendar.deleteAllExceptRemoteNames(LocalCalendar.java:268)
So it means there are really too many entries in this calendar. I’m quite surprised because I haven’t seen that yet. Given the limit is 1 MB and a file name is about 30 characthers, that would mean there are ~ 30000 calendar entries which seems quite much for me.
Can you confirm that you have that many entries?
It’s planned to provide a feature that synchronizes only events in a certain time interval (+/- n days from now), which will reduce the number of events. Until then, I recommend to create a new calendar with less entries or clean up (archive/delete) old events.