Classic Outlook profiles with POP accounts and PSTs hang after Windows updates on Jan. 13, 2026

Last Updated: January 21, 2026

ISSUE

After Windows updates on January 13, 2026 users with Outlook POP account profiles and profiles with PST files report that Outlook hangs and does not exit properly. This issue may occur for any Outlook profile that has PSTs stored on OneDrive.

Symptoms reported include:

• Outlook hangs and shows “Not Responding”.
• Inability to reopen Outlook without ending its process in Task Manager or restarting the computer.
• Emails not appearing in the Sent Items folder despite being sent.
• Outlook redownloading emails.

Affected platforms:

• Client: Windows 11, version 25H2; Windows 11, version 24H2; Windows 11, version 23H2; Windows 10, version 22H2; Windows 10 Enterprise LTSC 2021; Windows 10 Enterprise LTSC 2019
• Server: Windows Server 2025; Windows Server, version 23H2; Windows Server 2022; Windows Server 2019

STATUS: INVESTIGATING

For the latest status, please go to the Windows guidance on the Windows release health dashboard, Windows 11, version 25H2 known issues and notifications.

WORKAROUND

Until a fix is available, please use webmail. The other workarounds may be complicated. Please see the forum thread linked below for reference.

• Use webmail.
• Move PSTs out of OneDrive. For more information, please go to How to remove an Outlook .pst data file from OneDrive.
• Remove the Windows Update. For more information, please go to How to uninstall a Windows Update.

This issue is being discussed in the Learn forums if you want to ask questions or share feedback here:

• Outlook Classic not opening properly or recording sent mails after 2026-01 Security Update (KB5074109) (26200.7623)

Additional Resources

See Also​

Fixes or workarounds for recent issues in classic Outlook for Windows