Microsoft has started investigating several issues affecting the classic Outlook desktop client, after users reported email synchronization failures and server connection errors. The problems mainly affect users who connect Gmail or Yahoo accounts to Outlook or try to create groups inside the classic Outlook app.
These issues appear in the traditional Outlook client used in Microsoft 365 environments and can prevent users from syncing email folders, sending messages, or creating groups. Microsoft confirmed that its engineering team is currently analyzing the root cause and working on a permanent fix.
Classic Outlook Group Creation Bug Causes “Can’t Connect to Server”
One of the most reported issues occurs when users try to create groups in classic Outlook. After filling in the required details, Outlook displays a red error message saying:
“Can’t connect to the server.”
This issue occurs when Exchange Web Services (EWS) is enabled. Outlook attempts to validate group properties through an Active Directory Graph request, but the validation process fails with an internal server error.
The failure prevents Outlook from completing the group creation process.
Why This Happens
The problem occurs because the ValidateUnifiedGroupProperties API call fails, producing an internal server error. In this situation:
- The Azure AD Graph call fails
- Outlook cannot validate group configuration
- Group creation stops before completion
Microsoft confirmed that the current implementation in classic Outlook still relies on EWS-based group integration, which may cause compatibility issues.
Temporary Workaround
Until Microsoft releases a fix, users should create or manage Outlook groups using:
- Outlook Web Access (OWA)
- The new Outlook client
Both alternatives use newer APIs that avoid the current validation failure.
Gmail and Yahoo Accounts May Fail to Sync in Classic Outlook
Another issue currently under investigation affects Gmail and Yahoo email synchronization in classic Outlook.
Users report that Outlook stops syncing email folders after they change their Gmail or Yahoo password. In many cases, Outlook fails to prompt users to sign in again, which prevents the account from reconnecting.
Common Error Codes
Affected users may see errors such as:
- 0x800CCC0E
- 0x800CCC0F
- 0x80070057
These errors usually appear during send/receive operations or when Outlook tries to check for new mail.
How to Fix Outlook Gmail or Yahoo Sync Errors
Microsoft recommends deleting the affected Outlook identity from the Windows Registry to force Outlook to rebuild the account connection.
Steps to Apply the Workaround
- Press Windows + R to open the Run dialog.
- Type regedit and press Enter.
- Navigate to the following path:
Computer\HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Common\Identity\Identities- Look for the identity that matches the Gmail or Yahoo account that is not syncing.
- Delete the matching identity key.
- Restart Outlook.
- Sign in to the email account again.
After Outlook recreates the identity profile, synchronization usually resumes normally.
Microsoft Is Preparing Changes to Fix These Outlook Problems
Microsoft confirmed that the Outlook team is already working on updates to address these issues. One of the key changes includes replacing the older EWS-based functionality with modern REST API integrations.
This update should improve:
- Group management reliability
- Account authentication handling
- Email synchronization stability
The company has not announced a specific release date yet, but it plans to publish updates once the new implementation becomes available.
Should Users Switch to the New Outlook?
Microsoft is gradually encouraging organizations to migrate to the new Outlook client, which relies on modern cloud APIs instead of older technologies such as Exchange Web Services.
While classic Outlook remains widely used, the new client offers better compatibility with modern authentication systems and cloud services.
Organizations that rely heavily on Outlook groups or third-party email accounts may benefit from switching earlier to avoid these issues.
