Teams Meeting Add-in Prevents Some Users From Accessing Outlook Classic, Microsoft Confirms

Yesterday, Microsoft resolved a widespread Exchange Online outage that disrupted access to mailboxes and calendars across multiple platforms. The problem, logged under EX1253275, affected Outlook on the web, desktop clients, Exchange ActiveSync, and other Exchange Online connection protocols. That said, it seems Microsoft 365 apps are continuing to give headaches to users.

Microsoft is reportedly investigating the Teams Meeting Add-in issue affecting Classic Outlook users

Earlier today, Bleeping Computer, citing Microsoft Admin Center Message ID EX1254044, reported that the company has acknowledged a separate issue impacting the classic Outlook desktop client. Microsoft reportedly says that users with the Microsoft Teams Meeting Add-in enabled may be unable to access Outlook Classic due to a previous Outlook build.

At this point, the only workaround available for users is to update Outlook or perform an Online Repair for click-to-run installs, which reinstalls all Office applications. The company has further confirmed that it is working to push the latest version to mitigate this issue.

The news outlet also notes that the company is looking into other problems, including email connection errors, specifically 0x800CCC0F and 0x80070057, which occur when syncing with Gmail and Yahoo accounts.

For now, the only way to avoid the issue is by following the aforementioned workaround. We’ll update this article as soon as we get any news from Microsoft on a permanent fix.