Windows 11 Update Crashes Classic Outlook, Emails Lost

Microsoft's latest update for Windows 11, KB5074109, is causing significant issues for classic Outlook users, including app crashes and email loss.

Key Issues with Update

• The KB5074109 update disrupts classic Outlook on Windows 11.
• Users report freezing and loss of unsent emails.
• Suncoast Information Systems confirms uninstalling the update as a workaround.
• The update rolled out in January 2026.
• Switching to the new Outlook app is an alternative solution.

Impact on Users

The disruption has led to a loss of productivity as users struggle with the reliability of email communications. Many users are forced to uninstall the update or migrate to the new Outlook app to continue their work seamlessly.

Update: 17 Jun 2026