Microsoft 365 Alert – Service Degradation – Exchange Online – Admins may see some mailbox migrations to Exchange Online fail to complete and then restart – RESOLVED

21/04/2023 09:10:00 AM (GMT)

NHSmail Reference : INC35437592

Microsoft Reference : EX544221

Issue Status : RESOLVED

Issue Description : Admins may see some mailbox migrations to Exchange Online fail to complete and then restart.

More Information : When the issue first started, mailbox migrations were failing even after they restarted. Currently, the affected mailbox migrations appear to succeed after they automatically restart.

Final Update : 28/04/2023 10:53:00 AM – Microsoft’s telemetry shows that instances of this issue occurring after the fix have significantly dropped and this issue is resolved. While this issue was primarily affecting a specific folder, in which the fix was applied to address, there are some rare instances where other folders may see this error and be impacted. Due to the infrequent nature of this, the errors potentially affecting different folders cannot be predicted, and they recommend reaching out through our support channels for additional assistance. Please note that while the errors may occur, migrations are still expected to complete after the restart is done.

Scope of impact : This issue may impact any admins attempting to migrate mailboxes to Exchange Online.

Root cause : A recent change altered the source where the migration service selects a specific folder for copying during migrations, causing the incorrect folder to be selected and the copy job failing.

Next steps: Microsoft are reviewing the validation and update procedures to detect and prevent issues like this prior to deployment in the future.