Security & Infrastructure Tools
Microsoft investigates classic Outlook sync and connection issues
Microsoft is investigating several issues affecting the classic Outlook desktop client, including “Cannot connect to server” errors when creating groups with Exchange Web Services enabled, sync errors (0x800CCC0F/0x80070057) for Gmail and Yahoo accounts after password changes, a bug that hides the mouse pointer in Outlook and other Microsoft 365 apps, and an earlier issue preventing access to encrypted emails. The company is working on fixes—particularly replacing group functionality with REST APIs—and advises users to use the new Outlook client or OWA, delete problematic registry entries, or restart the computer as temporary workarounds until updates are released.
Microsoft has confirmed that several longstanding problems with the classic Outlook desktop client are still under investigation. The issues affect email synchronization and connectivity for users who rely on the legacy version of Outlook rather than the newer web or mobile apps.
1. Group Creation Errors
Users who have Exchange Web Services (EWS) enabled in their tenant experience a “Can’t connect to the server” error when trying to create new groups from classic Outlook. Microsoft has identified that this stems from an AD Graph call failing with an internal server error: “Both AAD and MSGraph clients are null or AAD Graph is disabled for this API.” The Outlook team is working on a fix that will replace the problematic EWS calls with REST APIs. Until the update lands, Microsoft recommends creating and editing groups using the new Outlook client or Outlook Web Access (OWA).
2. Gmail/Yahoo Sync Issues
Classic Outlook users who have recently changed their Gmail or Yahoo passwords are not prompted to re‑authenticate, leading to sync errors such as 0x800CCC0F and 0x80070057. Microsoft is still diagnosing the root cause of these failures and will provide a detailed solution once it’s available. As an interim workaround, affected users can delete the registry entries for the problematic email address under:
ComputerHKEY_CURRENT_USERSoftwareMicrosoftOffice16.0CommonIdentityIdentitiesin the Windows Registry Editor.
3. Mouse Pointer Disappearance
A less common but disruptive bug has been reported in which the mouse cursor disappears while using classic Outlook, affecting a handful of users and also causing similar issues in OneNote and other Microsoft 365 apps. The Outlook team is requesting affected customers to open a support case through their Microsoft 365 admin portal and submit diagnostic logs for analysis. Temporary fixes include clicking an email in the list (which may restore the cursor), switching to PowerPoint, editing content, and returning to Outlook, or simply restarting the computer.
4. Previous Bugs
In January, Microsoft addressed a separate classic Outlook issue that prevented users from opening encrypted emails after December 2025 updates. The company has since fixed that bug and released the corresponding patch.
Microsoft’s Outlook team is actively working on these issues and will update their support documentation once fixes are available. In the meantime, customers should use the newer Outlook clients or follow the outlined workarounds to mitigate the problems while waiting for a permanent resolution.