Microsoft 365 Copilot access issues under incident CP1470554; Copilot buttons still missing in classic Outlook

Microsoft is investigating Microsoft 365 Copilot access errors under Service Health incident CP1470554 with no root cause or recovery timeline published, and separately confirmed that Copilot buttons go missing in classic Outlook builds 20026.20182 and higher…

On 2026-09-11, Microsoft began investigating reports that users cannot open Microsoft 365 Copilot or encounter errors when interacting with it, tracked as incident CP1470554 in the Microsoft 365 admin center. Microsoft has not disclosed a root cause, affected regions, or estimated recovery time, and says the issue is not a breach or cyberattack; tenant admins are directed to the Service Health Dashboard. This followed several distinct Copilot availability failures between late August and September 10, including an authentication-configuration outage and a Copilot Chat configuration fault, and was described as the third distinct Copilot availability issue in recent weeks. In a 2026-09-16 update, Microsoft confirmed a related-sounding but distinct known issue: Copilot and Copilot Chat buttons disappear in classic Outlook for Windows after upgrading to build 20026.20182 and higher, because Outlook cannot locate the MAPI property PR_PROFILE_USER_SMTP_EMAIL_ADDRESS_W. The missing-button bug affects Copilot Chat (Basic) and paid Microsoft 365 Copilot (Premium) license holders. A temporary workaround is to enable 'Show Apps in Outlook' under File > Options > Advanced, and Copilot remains reachable via OWA, new Outlook, and the standalone app. Microsoft also acknowledged a separate known issue causing Outlook crashes tied to Kaspersky's Mail Checker (mcou.dll). The sources do not explicitly link the classic Outlook missing-button bug to incident CP1470554, and Microsoft has not confirmed whether they are the same incident.

• Incident ID: CP1470554, tracked in the Microsoft 365 admin center Service Health Dashboard (reported 2026-09-11).
• Symptom under CP1470554: users cannot open Microsoft 365 Copilot or encounter errors when interacting with it.
• For CP1470554, Microsoft has not published a root cause, affected regions, or estimated recovery time; Microsoft says it is not a breach or cyberattack.
• It followed several distinct Copilot availability failures between late August and September 10, 2026, including an authentication-configuration outage and a Copilot Chat configuration fault; described as the third distinct Copilot…
• Classic Outlook bug (reported 2026-09-16): Copilot and Copilot Chat buttons go missing after upgrading classic Outlook for Windows to build 20026.20182 and higher.
• Technical cause of the missing buttons: Outlook cannot locate the MAPI property PR_PROFILE_USER_SMTP_EMAIL_ADDRESS_W.
• Affected licenses: Copilot Chat (Basic) and paid Microsoft 365 Copilot (Premium).
• Workaround: enable 'Show Apps in Outlook' under File > Options > Advanced.