Microsoft 365 Alert – Service Degradation – Exchange Online – Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish – ONGOING

24/08/2026 09:30:00 AM

NHS.net Connect Reference: INC46916720

Microsoft Reference: EX1458145

Issue Status: ONGOING

Issue Description: Users may be unable to complete mailbox offboarding because the migration task is blocked and can’t finish.

Current Update: 24/08/2026 09:31:00 AM – Microsoft have been able to successfully disable the affected integrity validation process and resolve this issue for the majority of users. They are in the process of developing a code fix for the remaining impacted users and will provide an updated timeline on this final step in the remediation process as soon as it becomes available.

Scope of impact: Users attempting to complete mailbox offboarding in Exchange Online may be impacted by this issue. This section may be updated as our investigation continues.

Root cause: The mailbox migration task is being delayed due to the integrity validation process remained pending at the completion stage, resulting in impact.

Next update by: Tuesday, August 25, 2026, at 8:00 PM UTC