Thanks! I hope it helps. Unfortunately I am not able to reproduce that even on the work computer.
Exsiting Calendar Items cause Exception on first Launch
for DAVDroid 1.3.4-1-ose on Androdi 6.0.1, on first launch DAVDroid fails with exception of there are existing entries in the calendar.
When those calendar entries are copied to the server DAVDdroid experiences a Java Excveption and synchornization fails
To be able to use DAVDroid, all existing calendar entries must be removed