A current security update for Windows 11 is causing massive problems for users of the classic Microsoft Outlook. The result: application crashes and processes that can no longer be ended.
Update KB5074109which was delivered on January 13, 2026 as part of the monthly security updates, causes many users to experience a seemingly endless run OUTLOOK.EXE-Process. Although the program window is closed, the process remains active in the background. This prevents the client from restarting and forces users to take drastic measures: They have to manually end the process via the task manager or restart the entire computer in order to be able to access their emails again. In addition, users report that sent emails disappear and program windows freeze completely.
The update was actually supposed to deliver standard security patches and quality improvements for Windows 11. Instead, it solved one Regression that specifically affects Outlook session management. Users of the classic desktop version who access their email accounts via this are particularly affected POP protocol (Post Office Protocol) with locally stored PST files. With them, the process does not end correctly after closing. The operating system incorrectly assumes that Outlook is still running, which blocks a restart.
Advertisement
Is your Outlook stuck in the background after the update or are you noticing sent emails? The free Outlook special course shows step by step how to set up Outlook correctly, back up PST data and specifically fix problems with hanging OUTLOOK.EXE processes – including workarounds for POP accounts and a practical troubleshooting checklist. Ideal if you want to quickly and reliably access your emails again. Download the Outlook special course and troubleshooting guide now
The problem is not just limited to Outlook. Bugs were also fixed with KB5074109 Remote Desktop Connectionssystem shutdowns and random screen crashes introduced. Microsoft has already released emergency updates for some of these issues, but a specific fix for the Outlook bug was still pending as of January 19th.
Microsoft’s response and user workarounds
Microsoft has officially confirmed the issue as “under investigation” and issued a support alert. A permanent patch is still pending, but the development teams are working on a solution.
Affected users now have several options to restore functionality:
- Uninstall update: The safest solution is to remove the faulty update via
Einstellungen > Windows Update > Updateverlauf > Updates deinstallieren. - End process manually: Via Task Manager (
Strg+Umschalt+Esc) canOUTLOOK.EXE-Process must be terminated after closing to restart Outlook. - Switch to web version: Outlook im Web (OWA) is not affected by the bug and offers a working alternative.
- Pause updates: Until a permanent fix is available, users should temporarily suspend automatic Windows updates.
Quality control under pressure
The incident is part of a series of problems in which Windows updates unintentionally affect the stability of applications. It underlines the dilemma for IT administrators: On the one hand, security updates have to be installed promptly, but on the other hand, they threaten to introduce new bugs that hinder productivity.
For businesses, this is a reminder of the importance of one staggered update management. By first testing patches in a controlled testing environment, such issues can be identified before they affect the entire workforce. Users will now have to wait for a corrective update from Microsoft, which is expected to be included as an unscheduled patch or in the next monthly update.
