Microsoft 365 Alert – Service Degradation – Exchange Online – Users may be unable to upload attachments from Microsoft OneDrive in Outlook on the web and the new Outlook desktop app – RESOLVED

16/12/2025 09:10:00 AM

NHSmail Reference: INC46706439

Microsoft Reference: EX1193588

Issue Status: RESOLVED

Issue Description: Users may be unable to upload attachments from OneDrive in Outlook on the web and the new Outlook desktop app.

More info: When users attempt to upload files from OneDrive, they may receive an error that states: “We couldn’t retrieve the items you requested.” Additionally, the option to edit files in the browser is missing.

Final Update: 01/01/2026 08:33:00 AM – Microsoft have confirmed that the fix has completed releasing to all affected environments and validated this has remediated this issue using service telemetry.

Scope of impact: Any user attempting to upload attachments from OneDrive in Outlook on the web and the new Outlook desktop app may be impacted.

Root cause: A recent .NET framework update intended to improve performance for users introduced a misconfiguration, which is resulting in an extremely large increase in requests from Outlook on the web when retrieving the OneDrive URL. This increase in traffic is resulting in request queuing, timeouts, and throttling as a service protection measure, which is causing impact.