Microsoft Office Tutorials: The operation cannot be performed because the message has been changed

Last Updated: March 3, 2020

ISSUE

This applies to Outlook 2016 when connecting to Microsoft 365 mailboxes.

Consider the following scenario:

You are working in Cached mode in Microsoft Outlook.
You are granted delegate permission for another user's calendar.
In the other user's calendar, you create a meeting request, and then add users to the meeting through Scheduling Assistant.
You type meeting details in the request, and you wait for the request to be autosaved to the Drafts folder.
You add Skype or Teams meeting by selecting New Skype Meeting or New Teams Meeting on the ribbon.
You click Send to send the meeting invitation after the draft was potentially opened for several hours.

In this scenario, you may receive an error message that resembles the following:

Changes to the meeting cannot be saved. The meeting has been updated by another person. Close and reopen the meeting, and then make your updates. The operation cannot be performed because the message has been changed.

Error dialog

STATUS: FIXED

A fix has been implemented in the service starting with service build 15.20.2730.00 and higher. Use the Connection Status Dialog to confirm the service version: Description of the Connection Status dialog in Outlook.

This issue is caused by Exchange Based Assistants (EBAs) in the service writing edits to the meeting item causing a conflict resolution problem. The current fix is to skip all notifications on meeting drafts so that no EBA or ItemAssistant will get a chance to modify a meeting draft. When the meeting is updated from draft to non draft, the notification to EBAs and ItemAssistants proceed with edits on the meeting item. This solution will delay the EBAs and the error from happening for about 1.5 hours after you save the meeting. To avoid the conflict and the error, send the meeting within 1.5 hours of saving the meeting.

The Outlook Teams continue to work on a long term solution. When we have more specifics we will document them here.

More information and workaround steps for this issue can be found here: "The operation cannot be performed because the item has changed" error when a delegate creates a Skype or Teams meeting in Outlook.