Sync for user stops due to EventItemCountMismatchException Cancel The title field is required!

1. maximilian.muenst

   

   4 posts
   Registered:
   26 Jul 2016
   Answered

   14 Jan 2021

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   Sometimes I get the following error during synchronization of a user:
   
   The synchronization for this user is being stopped.
   Reason: Allocatus tried to get all calendar events for <username>.
   The query with the url: 'https://graph.microsoft.com/beta/me/events?...' returned 7598 items, but should have returned 7599 items. This mismatch of the item count can be caused by Microsoft Exchange or if you add/delete calendar events while Allocatus loads the events. To prevent problems in the synchronization Allocatus stops synchronizing this user in this cycle. In the next cycle this user will be synchronized normally again.
   
   What does this mean and is it a critical problem?
2. allocatus.admin

   

   39 posts
   Registered:
   17 May 2016
   14 Jan 2021 in reply to maximilian.muenst

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   maximilian.muenst said:
   What does this mean and is it a critical problem?

   
   
   Hi, 
   this is not a critical problem. This is a safety feature.
   During a sync cycle Allocatus loads all your calendar events from Microsoft Exchange to compare them to the data that Allocatus has in the database. We have experienced that Exchange sometimes does not deliver all of the items in an users calendar due to a problem in Exchange. If Allocatus gets less or more events as Exchange claims to have, we stop the synchronization as this could lead to unwanted behavior in Allocatus. E.g. Allocatus could recognize calendar events as deleted and re-add them to the calendar and then they are in the calendar twice. 
   In the next synchronization Allocatus will synchronize this user correct again.