Warning appears when viewing alerts for a mailbox in Microsoft Dynamics 365

This article provides a resolution for the issue that an ErrorIrresolvableConflict warning occurs when you view alerts for a mailbox in Microsoft Dynamics 365.

Applies to:   Microsoft Dynamics 365, Microsoft Dynamics 365 Customer Engagement Online
Original KB number:   4470093


When viewing alerts for a mailbox in Microsoft Dynamics 365, you see the following warning:

Appointments, contacts, and tasks for the mailbox [Mailbox Name] couldn't be synchronized. The owner of the associated email server profile [Profile Name] has been notified. The system will try again later.

The following additional details are also included:

Error : Exchange Error Code: ErrorIrresolvableConflict

Exchange Error Message : The operation can't be performed because the item is out of date. Reload the item and try again. Exchange Error Details: System.Collections.Generic.Dictionary`2[System.String,System.String]"


This warning may appear if Server-Side Sync attempted to update an item in Microsoft Exchange and an ErrorIrresolvableConflict message was returned by the Exchange server. This is typically a temporary issue and the item will be updated successfully during the next synchronization cycle.

For more information on Microsoft Exchange error codes such as ErrorIrresolvableConflict, see ResponseCode.


If this message does not persist on the next synchronization cycle (typically 15 minutes), this warning can be ignored. If this message persists, you can contact Microsoft Support.