Conflict Message Error when trying to Open a Meeting Invite

Here is the Known Issue article, Outlook shows conflict errors when updating or cancelling meetings - Microsoft Support. The service teams are working on a fix and hopefully be going out soon. In the meantime, I would make any important meeting updates from OWA or New Outlook or Teams.

If you see items on your calendar that have the diamond you can use the steps in the Known Issue to Clear Offline Items for your calendar to clean it up. That step removes the local item that is in conflict and will pull down a good copy when it syncs next. The conflict is only on your computer and not recipients or the cloud version of it.

If you got the Conflict Message dialog and clicked Keep All it would have created duplicates. I am adding some steps to the Known Issue article for Monday to use the Calcheck tool to remove the duplicates. Otherwise you could cancel all instances and send a new meeting invite. I saw some users got hundreds of copies and the Calcheck solution should help with that.

i have this same issue that started july 2. please advise resolution

Until the fix gets deployed in the service it would be best to create or update meetings in OWA or New Outlook. This issue is something that can unexpectedly happen and not something you can anticipate.

The issue is tracked in the Service Health Dashboard as EX800425.

Here is the latest update:

Title: Users may intermittently be unable to update or cancel calendar items in the Outlook desktop client

User impact: Users may intermittently be unable to update or cancel calendar items in the Outlook desktop client.

More info: Users intermittently receive an error when updating or canceling calendar items that prevent these users from completing the intended action.

As a potential workaround, users can try updating meetings using the new Outlook desktop client or Outlook on the web (outlook.office365.com/calendar/view/day).

Additional information on the end user experience and error messages being received can be found here: support.microsoft.com/en-us/office/outlook-shows-conflict-errors-when-updating-or-cancelling-meetings-69c26227-40ef-4377-8f12-1749fcaad2ad

Current status: The code change to adjust how the server identifies the most accurate version of the Outlook meeting event is in the process of being deployed to our internal environment. We anticipate being able to run testing to validate this change as a fix within the next 48 hours. If our testing proves this change to be an effective fix, we’ll provide a roll out timeline for all environments.

Scope of impact: This event may intermittently impact users updating or canceling calendar items in the Outlook desktop client.

Next update by: Friday, July 5, 2024, at 10:00 PM UTC

I recently started experiencing the same problem and it only seems to affect the meetings I create using Outlook (Windows, Office 365 in a corporate environment). I have never experienced this in meetings created by my colleagues.