Troubleshooting Outlook: Microsoft’s Investigation into Sync and Connection Problems

Microsoft Investigating Email Synchronization and Connection Issues in Classic Outlook

Microsoft is currently looking into various issues affecting email synchronization and connection in the classic Outlook desktop client. These issues are causing inconvenience to users and disrupting their workflow.

First Bug Causing Connection Errors

One of the bugs reported causes “Can’t connect to the server” errors when users attempt to create groups in classic Outlook with Exchange Web Services (EWS) enabled for the tenant. Microsoft attributes this issue to a specific error in the AD Graph call for ValidateUnifiedGroupProperties.

According to Microsoft, the error message indicates “An internal server error occurred. The operation failed. Both AAD and MSGraph clients are null or AAD Graph is disabled for this API.” The Outlook team is actively working on a solution and plans to release updated group functionality that uses REST APIs to address this issue.

Until a fix is available, Microsoft recommends affected users to create and edit groups using the new Outlook client or Outlook Web Access (OWA) as temporary alternatives.

Other Known Issue with Gmail and Yahoo Accounts

Another known issue involves triggering error codes 0x800CCC0F and 0x80070057 when synchronizing Gmail and Yahoo accounts in classic Outlook. Users have reported issues after changing passwords for these accounts, where they are not prompted to sign in again.

Microsoft is actively investigating this issue and working on a solution. In the meantime, affected users can delete the registry entries for the affected email addresses under the Identities key in the Windows Registry Editor to work around the synchronization problems.

Mouse Pointer Disappearance Bug

Microsoft is also looking into a bug in classic Outlook that causes the mouse pointer to disappear for some users. This issue has been acknowledged after reports surfaced online and also affects users of OneNote and other Microsoft 365 apps.

Affected customers are advised to open a support case with the Outlook Support Team and submit diagnostic log files to assist with analysis. Temporary workarounds include clicking an email in the message list when the cursor disappears or switching to PowerPoint and then returning to Outlook to restore the mouse pointer. Restarting the computer may also temporarily resolve the issue.

Addressing Previous Encryption Issue

In January, Microsoft resolved another issue in classic Outlook caused by updates in December 2025 that prevented Microsoft 365 customers from opening encrypted emails.