Why does not Calendar.app sync to exchange calendar on Mac OS X? My problem is not this or this. 

Error message: "There was an error saving ical data. Calendar App encountered a critical error while saving to the database, and recent changes may be lost. More information may be available in the console."

It is very similar to this question.

However my console log has such entries:

09.11.15 11:54:53,484 CalendarAgent[2263]: CoreData: XPC: Token mismatch
09.11.15 11:54:53,485 suggestd[379]: [com.apple.calendar.store.log.notifications] [There was an error when fetching NOBOs for principals: (Local) (error: Error Domain=NSCocoaErrorDomain Code=134095 "(null)" UserInfo={Problem=request failed, store identifier mismatch})]
09.11.15 11:54:53,488 CalendarAgent[2263]: CoreData: XPC: Token mismatch
09.11.15 11:54:53,489 suggestd[379]: [com.apple.calendar.store.log.notifications] [There was an error when fetching NOBOs for calendars: () (error: Error Domain=NSCocoaErrorDomain Code=134095 "(null)" UserInfo={Problem=request failed, store identifier mismatch})]


When I setup my exchange account, first sync works good but after init sync it does not work anymore and I get this error. Well, when I deactivate my Exchange cal, delete all cache files and activate it again, it syncs for one time and then again not. But this is not a solution. 

It seems like a bug - but I am not sure what to do now. Busycal costs 50€ and since Calendar.app is with Mac OS X, I thought they might fix this issue soon?
I found these steps on the Apple site and modified them - the modifications work.


open Calendar
Calendar -> Accounts
Disable exchange calendars
Reboot


Now re-enable


open Calendar
Calendar -> Accounts
Enable exchange calendars