Microsoft 365 Alert – Service Degradation – Microsoft 365 suite – Users can’t get some calendar information through Graph APIs in various Microsoft 365 services and receive a 500 error – RESOLVED

Announcements Arpan Das

20/06/2025 07:43:00 AM

NHSmail Reference: INC46550223

Microsoft Reference: MO1089340

Issue Status: RESOLVED

Issue Description: Users can’t get some calendar information through Graph APIs in various Microsoft 365 services and receive a 500 error.

Final Update: 08/07/2025 08:35:00 AM – Following the deployment of Microsoft’s solution, their internal testing has validated that the conflict within the code has been addressed and that impact has been remediated.

Scope of impact: Your organization is affected by this event, and some users attempting to get calendar information through Graph APIs are impacted.

Root cause: Changes related to deprecating Skype introduced a conflict within the code leveraged during the retrieval of some calendar information through Graph APIs, which is resulting in impact.

Next steps: Microsoft are further analyzing the isolated code conflict to help them improve their pre-deployment testing and validations and to help prevent similar issues in the future.