KMS

Microsoft Confirms November 2026 Patch Tuesday Updates Trigger Windows Activation Failures with Error 0x80041008

Microsoft has confirmed that the November 2026 Patch Tuesday security updates are causing Windows activation and licensing failures on multiple client and server platforms. The issue manifests as error code 0x80041008 when organizations run SLMGR commands to activate Windows, configure KMS, or manage product keys. Affected systems include Windows 10 21H2, Windows 10 22H2, Windows 11 23H2, Windows Server 2019, Windows Server 2022, and Windows Server 2025. Devices already activated or using pre-configured KMS client keys without SLMGR remain unaffected. Microsoft stated that a fix will be released in the coming days and recommended contacting support for immediate mitigation. This marks the second known Windows activation problem reported by the company in 2026.