How can I fix an “error when fetching NOBOs” when exchange calendar syncs to 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: CoreData: XPC: Token mismatch 09.11.15 11:54:53,485 suggestd: [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: CoreData: XPC: Token mismatch 09.11.15 11:54:53,489 suggestd: [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?