User impact: Users may have been intermittently unable to download attachments or view embedded images in Outlook on the web.

More info: Users may have seen the following error message when an attachment failed to download: “Error downloading the file content.” This issue may have impacted those who were downloading attachments or viewing embedded images in Outlook on the web.

To ensure the mitigation takes effect, users should log out and then log in to their Outlook on the web accounts. If available, users could have downloaded attachments and viewed embedded images consistently through the Outlook desktop client or the Outlook mobile app.

Final status: We’ve completed the deployment of the fix and service telemetry indicates availability has been restored. Customers have also reported that the issue is resolved. If users are still experiencing the issue, please ensure that they log out and log back in to their devices for the changes to take effect.

Scope of impact: Users attempting to download attachments and viewing embedded images in Outlook on the web may have been intermittently impacted.

Start time: Friday, March 29, 2024, at 12:00 AM UTC

End time: Monday, April 15, 2024, at 2:00 PM UTC

Root cause: A recent update that was intended to improve the reliability of Outlook on the web contained a code configuration issue that caused long running sessions, which may have prevented attachment downloads and embedded image viewing.

Next steps:
– We’re reviewing our change management procedures to identify opportunities for improvement with impact scenarios such as this.
– We’re performing analysis on our automated detections to determine more expedient methods to identify and resolve similar events in the future.

We’ll provide a Post-Incident Report within 5 business days.