Microsoft says the August 2026 security update can cause 0xc0000409 errors on Windows Server 2016 systems when the Compatibility Appraiser diagnostic service is enabled, leading to recurring CompatTelRunner.exe crashes. The issue affects physical and virtual machines, including VMware and Azure environments, and Microsoft plans to address it in a future update. #Microsoft #WindowsServer2016 #CompatTelRunner.exe #CompatibilityAppraiser #VMware #Azure
Keypoints
- The August 2026 Windows security update may trigger 0xc0000409 errors on Windows Server 2016.
- CompatTelRunner.exe crashes when the Compatibility Appraiser diagnostic service is enabled.
- The issue affects both physical devices and virtual machines.
- Microsoft says the problem does not affect device functionality.
- A permanent fix will arrive in a future Windows update.