Users may experience an error when updating a meeting in their own or a shared calendar

Last Updated: February 20, 2025

ISSUE

When a user updates a meeting in their own calendar or a shared calendar, they may experience one or more of the following errors: 

"The function cannot be performed because the message has been changed”

“The item cannot be saved because it was changed by another user or in another window”

"The operation cannot be performed because the message has been changed”

"The operation cannot be performed because the object has been deleted”

STATUS: INVESTIGATING

The Outlook team is investigating this issue. There are reports of such errors through specific workflows connected with service Event Based Assistant routines. This issue can be avoided or resolved by adjusting the profile setup and waiting 1-2 minutes before committing your changes to the calendar events or dismissing the error message and proceeding with saving your changes.

We do not have an ETA for a potential fix and will update this topic when we know more. For those that have support cases open, or if you are opening a case, please collect the following logs and share them with your support engineer.

1. Only before reproducing the error, add this registry key: 

   HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Options 
   DWORD: EnableConflictLogging 
   Value: 1

   Note: It is very important to delete the EnableConflictLogging registry key after the repro steps are complete and Outlook is closed. Do not leave this key enabled for any length of time after the repro is complete. 

2. After reproducing the error, immediately close Outlook. Collect all of the logs with file extension .etl from the time of the repro. The log files are stored in the Outlook Logging subfolder of the Temp folder. By default, your Temp folder is located in your \AppData\Local folder: c:\Users\"username"\AppData\Local\Temp. 

   By default, the Local Settings and AppData folders are hidden. To display hidden folders in Windows, do the following:

   1. In Windows, open Control Panel.

   2. Open Folder Options.
      
      - To locate Folder Options, in the search box at the top of window, type Folder Options.

   3. On the View tab, in Advanced settings, go to Files and Folders, then under Hidden files and folders, select Show hidden files, folders, and drives.

3. Delete the EnableConflictLogging registry key from step 1. Do not leave this key enabled for any length of time after the repro is complete.

4. Get Calendar Diagnostic Logs for each meeting that is reproducing the error, from the calendar owner, and any user with permissions to that calendar. For more information, go to Get calendar diagnostic logs for Exchange Online mailboxes.

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