Outage in Microsoft 365
Some users may not be able to access Exchange Online through Outlook on the web and are returned an error message
Resolved Minor
May 05, 2026 - Started 1 day ago
- Lasted about 2 hours
Incident Report
Summary AI Generated
A code regression in a Microsoft 365 service update caused some users in Europe to receive "Page not found" errors when accessing Exchange Online through Outlook on the web for 1.7 hours. Users reported being repeatedly logged out of Microsoft services during the incident. Microsoft resolved the issue by rolling back the problematic update, while users could access their email through Outlook desktop or mobile clients as a workaround.
Title: Some users may not be able to access Exchange Online through Outlook on the web and are returned an error message
User impact: Users may not be able to access Exchange Online through Outlook on the web and are returned an error message.
More info: Users with access to the Outlook desktop or mobile client may use these to bypass impact while we investigate the issue.
Affected users may be returned a "Page not found" error message when attempting to access their Exchange Online mailboxes using Outlook on the web.
Current status: We're investigating a potential issue with Exchange Online and checking for impact to your organization. We'll provide an update within 30 minutes.
Components affected
Exchange OnlineTrusted by 1,000+ teams
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Latest Updates ( sorted recent to last )
1 day ago - at 05/05/2026 06:46PM
Title: Some users may not be able to access Exchange Online through Outlook on the web and are returned an error message
User impact: Users may not be able to access Exchange Online through Outlook on the web and are returned an error message.
More info: Users with access to the Outlook desktop or mobile client may use these to bypass impact while we investigate the issue.
Affected users may be returned a "Page not found" error message when attempting to access their Exchange Online mailboxes using Outlook on the web.
Current status: We determined that a recent service update contained a code regression, which is resulting in impact when accessing Outlook on the web. We've rolled back the responsible update and are monitoring this action to confirm full remediation.
Scope of impact: This event impacts some users in Europe, who may not be able to access Exchange Online through Outlook on the web.
Start time: Tuesday, May 5, 2026, at 5:35 AM UTC
Root cause: A recent service update contained a regression, which is resulting in impact when accessing Outlook on the web.
Next update by: Tuesday, May 5, 2026, at 8:00 PM UTC
1 day ago - at 05/05/2026 06:17PM
Title: Some users may not be able to access Exchange Online through Outlook on the web and are returned an error message
User impact: Users may not be able to access Exchange Online through Outlook on the web and are returned an error message.
More info: Users with access to the Outlook desktop or mobile client may use these to bypass impact while we investigate the issue.
Affected users may be returned a "Page not found" error message when attempting to access their Exchange Online mailboxes using Outlook on the web.
Current status: We're investigating a potential issue with Exchange Online and checking for impact to your organization. We'll provide an update within 30 minutes.
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