SHD / MC Checker

[serviceDegradation] EX1056704 | Exchange Online | Users may see a 503 error when starting Outlook (classic) in online mode or utilizing the Exchange admin center (EAC)



EX1056704 | Exchange Online | Users may see a 503 error when starting Outlook (classic) in online mode or utilizing the Exchange admin center (EAC)

Status serviceDegradation
Classification advisory
User Impact Users may see a 503 error when starting Outlook (classic) in online mode or utilizing the EAC.
Last Updated 04/25/2025 14:31:01
Start Time 04/14/2025 00:00:00
End Time
Latest Message Title: Users may see a 503 error when starting Outlook (classic) in online mode or utilizing the Exchange admin center (EAC)

User impact: Users may see a 503 error when starting Outlook (classic) in online mode or utilizing the EAC.

More info: Some users intermittently may be unable to start Outlook (classic) when in working online mode and encounter the following error: “HTTP 503 Service Unavailable.”

Additionally, when attempting to complete operations in the Exchange admin center (EAC), admins are returned a “503 Service Unavailable” error.

Current status: Our analysis of call stack logs related to the workload management module and suitability verifier in the directory layer is ongoing. We’re analyzing these stack logs to identify a potential correlation in the data, to aid in identifying the root cause and help developing a mitigation plan. We’re continuing to investigate connectivity issues and high latency in provisioning handler calls, and its impact on service performance.

Scope of impact: Any user who attempts to start Outlook (classic) when working in online mode or utilize the EAC may be impacted by this event.

Start time: Monday, April 14, 2025, at 12:00 AM UTC

Next update by: Friday, April 25, 2025, at 8:00 PM UTC