Windows 10/11: June update can prevent Outlook and App from starting, bug fix available

[German]On Windows systems, it was possible that Microsoft Outlook or other 32-bit apps or applications were prevented from starting after installing the June 13, 2023 security updates. The issue occurred in conjunction with anti-virus, anti-malware or security software from certain vendors (Trellix was named). Trellix resolved the issue by releasing an update.

Apps are blocked after update installation

Installing the June 13, 2023 security updates could potentially prevent Microsoft or third-party apps from opening. Microsoft describes the following boundary conditions in the Windows Health Dashboard in the support article Microsoft Outlook and some apps might not open:

After installing Update xxx or later updates on Windows devices with certain antivirus, antimalware or security software installed, you might not be able to open Microsoft or third-party apps. Some known affected apps are Microsoft Outlook and other Microsoft Office apps.

This issue only occurs with 32-bit apps running on 64-bit Windows with Trellix Endpoint Security version earlier than 35.31.25. When attempting to open an affected app, Event Log indicates an access violation with the error "module is unknown".

The following Windows versions were affected once the listed updates from June 13, 2023 were installed:

• Windows 11 21H2 – 22H2; Update KB5027231; KB5027223
• Windows 10 21H2 – 22H2; Update KB5027215
• Windows Server 2022; Update KB5027225

This issue primarily affects Trellix Endpoint Security in above scenarios, so home users were rather unaffected.

Trellix releases a fix

This bug has been fixed by Trellix in Endpoint Security Agent (HX) 35.31.25 and later. If this issue occurs with other security software installed, or continues to occur on systems with the latest version of Trellix Endpoint Security Agent installed, affected individuals should contact customer support at the vendor of the security software they are using. Has anyone been affected by this issue?

Similar articles:
Patchday: Windows 10-Updates (June 13, 2023)
Patchday: Windows 11/Server 2022-Updates (June 13, 2023)