| DZ1193516 | Microsoft Defender XDR | Some admins may encounter errors when accessing Microsoft Defender for Endpoint features |
|---|
| Status | serviceDegradation |
|---|---|
| Classification | incident |
| User Impact | Admins may encounter errors when accessing Microsoft Defender for Endpoint features. |
| Last Updated | 12/09/2025 16:16:55 |
| Start Time | 12/09/2025 06:56:28 |
| End Time | |
| Latest Message | Title: Some admins may encounter errors when accessing Microsoft Defender for Endpoint features
User impact: Admins may encounter errors when accessing Microsoft Defender for Endpoint features. More info: Admins and security operators may encounter errors and failures when accessing multiple pages specific to Microsoft Defender for Endpoint in the Microsoft Defender portal. Impacted experiences include but may not be limited to: – Device Inventory In addition, API requests may return ‘431 Request Header Fields Too Large’ errors. Current status: Review of service health telemetry indicates the rollback failed to reach all of the affected infrastructure. We’ve initiated a new rollback to validate if the suspected service update is causing impact, and in parallel we’re testing a fix within a portion of the affected service infrastructure as a secondary remediation plan in case the rollback doesn’t resolve the impact. We anticipate the rollback will complete by our next scheduled communications update. Scope of impact: Admins and security operators attempting to access the Microsoft Defender for Endpoint experiences listed above via the Microsoft Defender portal, or to make MDE API calls, may be impacted. Start time: Thursday, December 4, 2025, at 10:00 AM UTC Next update by: Tuesday, December 9, 2025, at 8:00 PM UTC |