💡 Our Technical Review in summary
Summary
Microsoft investigated a reported issue where IT Administrators were unable to complete mailbox migrations within Exchange Online. While initial reports suggested a service configuration change related to request routing optimization was causing failures, a thorough investigation concluded that no service incident actually occurred.
Impact
The suspected impact was limited to multi-geo tenants. Specifically, administrators attempting to complete mailbox migration tasks reported difficulties; however, the service has been verified as healthy.
Status
Final Status: False Positive. Microsoft has determined that the service is performing as expected and no underlying incident was found. The investigation is complete, and this event is now closed.
Microsoft Official Issue Details
User Impact
Admins may be unable to complete mailbox migrations in Exchange Online.
Status: falsePositive
Service: Exchange Online
Classification: advisory
Origin: microsoft
Updates
- 2026-02-04 17:19
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Final status: The investigation is complete and we’ve determined the service is healthy. A service incident didn’t actually occur. This communication will expire in 24 hours.
This is the final update for the event.
- 2026-02-03 18:30
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Current status: We’ve confirmed that the configuration change to the migration mailbox and system mailbox locations didn’t remediate the issue. We’re investigating to determine alternative mitigation options and to better understand the underlying cause.
Scope of impact: Multi-geo admins may be unable to complete mailbox migrations in Exchange Online. This information may be updated as our investigation continues.
Root cause: A recent service configuration change, intended to optimize how requests are routed within the service, is resulting in impact.
Next update by: Wednesday, February 4, 2026, at 7:00 PM UTC
- 2026-02-03 14:47
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Current status: We’re continuing to implement a configuration change to the migration mailbox and system mailbox locations for some admins who reported that they are still impacted after disabling the setting.
Scope of impact: Multi-geo admins may be unable to complete mailbox migrations in Exchange Online. This information may be updated as our investigation continues.
Root cause: A recent service configuration change, intended to optimize how requests are routed within the service, is resulting in impact.
Next update by: Tuesday, February 3, 2026, at 6:30 PM UTC
- 2026-02-03 13:12
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Current status: We’ve determined that our previous action of disabling the setting has mitigated impact for the majority of affected admins. We’re implementing a configuration change to the migration mailbox and system mailbox locations for some admins who reported that they are still impacted after disabling the setting.
Scope of impact: Multi-geo admins may be unable to complete mailbox migrations in Exchange Online. This information may be updated as our investigation continues.
Root cause: A recent service configuration change, intended to optimize how requests are routed within the service, is resulting in impact.
Next update by: Tuesday, February 3, 2026, at 3:30 PM UTC
- 2026-02-03 11:24
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Current status: We’ve disabled a setting to mitigate impact but this hasn’t resolved the issue. We’re analyzing fresh HTTP Archive format (HAR) files to determine why impact still persists.
Scope of impact: Multi-geo admins may be unable to complete mailbox migrations in Exchange Online. This information may be updated as our investigation continues.
Root cause: A recent service configuration change, intended to optimize how requests are routed within the service, is resulting in impact.
Next update by: Tuesday, February 3, 2026, at 1:30 PM UTC
- 2026-02-02 09:43
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Current status: We’ve determined that a recent service configuration change, intended to optimize how requests are routed within the service, is resulting in impact. We’re actively reviewing mitigation options and working to remediate the issue.
Scope of impact: Multi-geo admins may be unable to complete mailbox migrations in Exchange Online. This information may be updated as our investigation continues.
Root cause: A recent service configuration change, intended to optimize how requests are routed within the service, is resulting in impact.
Next update by: Tuesday, February 3, 2026, at 11:30 AM UTC
- 2026-02-02 05:28
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
Current status: We’re reviewing the provided case details and HTTP Archive format (HAR) logs to better understand the cause of impact and to help inform our next steps.
Scope of impact: Multi-geo admins may be unable to complete mailbox migrations in Exchange Online. This information may be updated as our investigation continues.
Next update by: Monday, February 2, 2026, at 10:00 AM UTC
- 2026-02-02 05:02
Title: Admins may be unable to complete mailbox migrations in Exchange OnlineUser impact: Admins may be unable to complete mailbox migrations in Exchange Online.
More info: This issue only affects multi-geo tenants.
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.
