Microsoft Investigates Classic Outlook Bugs Causing Sync Failures and Server Errors

Microsoft is investigating several new problems affecting the classic Outlook desktop client, shortly after acknowledging a missing cursor bug in the same application. The newly reported issues involve email synchronization failures and connection errors when managing groups.

Group creation bug causes “Can’t connect to the server” error

One of the problems causes a “Can’t connect to the server” error when users attempt to create groups in classic Outlook while Exchange Web Services (EWS) is enabled.

According to Microsoft, the issue occurs because the Active Directory Graph call responsible for validating group properties fails. Specifically, the ValidateUnifiedGroupProperties request returns an internal server error, preventing Outlook from completing the operation.

The Outlook team says it is working on updated group functionality based on REST APIs. Microsoft expects this change to resolve the problem once the updated implementation becomes available.

Until the fix is released, Microsoft recommends that users create or manage groups using the new Outlook client or Outlook Web Access (OWA) instead of the classic desktop version.

Gmail and Yahoo accounts may fail to sync in classic Outlook

Another issue currently under investigation affects Gmail and Yahoo email account synchronization in classic Outlook.

Users may encounter error codes 0x800CCC0F or 0x80070057, particularly after changing their Gmail or Yahoo account passwords. In these situations, Outlook sometimes fails to prompt users to sign in again, which prevents the account from reconnecting properly.

As a temporary workaround, Microsoft advises deleting registry entries associated with the affected email account. These entries are located under the following registry path:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities

Microsoft is also asking affected organizations to open support cases through the Microsoft 365 admin portal and provide diagnostic logs to help the company investigate the issue further.

Other Outlook changes are also on the way

In related Outlook developments, Microsoft is preparing additional changes to the platform. The company recently confirmed that Outlook will receive automapped calendar support, while the planned enterprise migration from classic Outlook to the new Outlook client has been delayed until next year.

Via Bleeping Computer