Microsoft 365 Alert – Service Degradation – Exchange Online – Users can’t upload attachments larger than 2 MB with Microsoft Graph API in Exchange Online – RESOLVED

21/03/2025 08:32:00 AM

NHSmail Reference: INC46509587

Microsoft Reference: EX1058997

Issue Status: RESOLVED

Issue Description: Users can’t upload attachments larger than 2 MB with Microsoft Graph API in Exchange Online.

More info: The provided article details the MB range for messages affected and more details on the Microsoft Graph API “createUploadSession” being utilized:
https://learn.microsoft.com/en-us/graph/api/attachment-createuploadsession?view=graph-rest-1.0&tabs=http

Final Update: 24/04/2025 09:00:00 AM – Microsoft have completed reverting the offending changes and have confirmed after a period of monitoring that impact was remediated.

Scope of impact: Your organization is affected by this event, and all users can’t upload attachments larger than 2 MB with Microsoft Graph API’s “createUploadSession” in Exchange Online.

Root cause: A recent update to the Exchange Online service contained an incorrect authentication configuration for the Microsoft Graph API “createUploadSession” used to upload files, which results in users being unable to upload attachments larger than 2 MB in Exchange Online.

Next Steps: To help prevent similar impact in the future, Microsoft are further reviewing their update release procedures to identify authentication configuration issues before being deployed.