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Intermittent Outlook.com authentication failures during ongoing service degradation

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1 unique sources, 1 articles

Summary

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Microsoft is addressing an ongoing service degradation affecting Outlook.com, causing intermittent authentication failures, unexpected sign-outs, and "too many requests" errors since April 27, 2026. The issue prevents users from accessing mailboxes and has generated thousands of reports on outage monitoring platforms. Investigation indicates client sign-in scenarios may be contributing to the behavior, and Microsoft is validating service component interactions. No root cause, affected user count, or regional scope has been disclosed.

Timeline

  1. 27.04.2026 15:03 1 articles · 3h ago

    Outlook.com authentication failures and unexpected sign-outs reported during ongoing service degradation

    Microsoft confirms an ongoing service degradation impacting Outlook.com, causing intermittent sign-in failures, "too many requests" errors, and unexpected sign-outs since April 27, 2026. Investigation focuses on client sign-in scenarios, with no disclosed root cause, affected user count, or regional scope. Outage monitoring platforms report thousands of user complaints.

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Information Snippets

  • Outlook.com users report intermittent sign-in failures, unexpected sign-outs, and "too many requests" errors during an ongoing service degradation event.

    First reported: 27.04.2026 15:03
    1 source, 1 article
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  • Microsoft confirmed the incident began over three hours prior to its latest update and is investigating client sign-in scenarios as a potential contributing factor.

    First reported: 27.04.2026 15:03
    1 source, 1 article
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  • Outage monitoring service Downdetector received thousands of user reports, indicating widespread user impact across multiple regions.

    First reported: 27.04.2026 15:03
    1 source, 1 article
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  • Microsoft has labeled the incident as "service degradation," signifying noticeable but non-total service disruption.

    First reported: 27.04.2026 15:03
    1 source, 1 article
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  • In March 2026, Microsoft mitigated a separate Exchange Online outage that blocked access to mailboxes and calendars via Outlook on the web, Outlook desktop, Exchange ActiveSync, and other protocols.

    First reported: 27.04.2026 15:03
    1 source, 1 article
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