Microsoft 365 Alert – Service Degradation – Microsoft Defender XDR – Users may see failures when querying the Microsoft Graph Attack Simulation Training API with $Select OData query – ONGOING

24/08/2026 09:26:00 AM

NHS.net Connect Reference: INC46916773

Microsoft Reference: DZ1459263

Issue Status: ONGOING

Issue Description: Users may see failures when querying the Microsoft Graph Attack Simulation Training API with $Select OData query.

More info: The issue is specifically happening when using “$Select” as part of the query.

Affected users can bypass the issue by not using “$Select” in the queries.

Current Update: 02/09/2026 09:25:00 AM – Microsoft has completed the validation within their internal testing environment and begun initiating the fix deployment. As the deployment begins to propagate throughout the affected service environment, they anticipate that some users may experience relief from impact. Additionally, they expect that they will have acquired a complete remediation timeline by their next scheduled update.

Scope of impact: This issue may impact any user querying the Microsoft Graph Attack Simulation Training API with $Select OData in Microsoft Defender. This section may be updated as our investigation continues.

Root cause: A code regression after a recent service update is impacting OData $Select query, causing failures.

Next update by: Tuesday, September 15, 2026, at 4:00 AM UTC