Microsoft 365 Alert – Service Degradation – Exchange Online – Users may be unable to download or open email attachments in Outlook on the web – ONGOING

15/04/2026 8:39:00 AM

NHSmail Reference: INC46799554

Microsoft Reference: EX1275040

Issue Status: ONGOING

Issue Description: Users may be unable to download or open email attachments in Outlook on the web.

More info: This issue may intermittently impact some users who attempt to access the Exchange Online service through the Outlook mobile apps or the new Outlook for Mac desktop client.

Current Update: 15/04/2026 8:40:00 AM– Our HAR trace analysis has focused our investigation to a token failure that we believe could be preventing the opening of email attachments for users in Outlook on the web. We’re further analyzing the isolated failure to confirm our findings and so our next troubleshooting steps for remediating the impact can be determined.

Scope of impact: Some users attempting to download or open email attachments in Outlook on the web are impacted. This information may be updated as our investigation continues.

Next update by: Friday, April 17, 2026, at 8:00 PM UTC