💡 Our Technical Review in summary
1. Summary
Microsoft is addressing a service degradation in Exchange Online where administrators are experiencing failures during tenant-to-tenant (T2T) migrations and mailbox offboarding moves. The issue is caused by a code regression in the Mailbox Replication Service (MRS), which prevents property tags from being properly configured, resulting in the error: PropTagToPropertyDefinitionConversionException.
2. Impact
This issue specifically affects IT Administrators attempting to move mailboxes between tenants or offboard them from Exchange Online. Affected migration batches or individual move requests may stall or fail to complete.
3. Status
Current State: Microsoft has isolated the offending change and is in the final stages of developing a code fix. Testing and validation are currently underway to ensure the fix remediates the impact without further regressions.
Workaround: While a long-term fix is being deployed, admins can bypass the error using PowerShell. Run the following commands for affected mailboxes:
Set-MoveRequest "[email protected]" -SkipMoving FolderRestrictionsResume-MoveRequest "[email protected]"(or resume the migration batch via the Admin Center)
Next Update: Expected by Thursday, February 26, 2026.
Microsoft Official Issue Details
User Impact
Admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange Online.
Status: serviceDegradation
Service: Exchange Online
Classification: advisory
Origin: microsoft
Updates
- 2026-02-20 20:59
Title: Some admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange OnlineUser impact: Admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange Online.
More info: While we work on developing a long-term solution, admins may use PowerShell for the affected migrations and moves with the following cmdlet against the affected mailboxes:
Set-MoveRequest “[email protected]” -SkipMoving FolderRestrictions
The tenant admin may then resume the move request (Resume-MoveRequest “[email protected]”) or simply resume the migration batch. This will allow the affected move jobs to continue to make progress.
Admins attempting to complete a tenant-to-tenant migration or an offboarding move in Exchange Online will be returned the following error “PropTagToPropertyDefinitionConversionException”
Current status: We’re in the final stages of the development of our solution to address the code regression and we’re preparing to begin testing this fix to validate that it’ll successfully remediate the impact. We’ll provide a timeline for resolution as one becomes available.
Scope of impact: Some admins attempting to perform tenant to tenant migrations and offboarding moves in Exchange Online may be affected. This information may be updated as our investigation continues.
Root cause: A change introduced a code regression to Mailbox Replication Service (MRS), which causes intermittent failures for tenant-to-tenant migration actions or offboarding moves as the property tags needed to complete the request are not being properly configured.
Next update by: Thursday, February 26, 2026, at 10:00 PM UTC
- 2026-02-17 21:12
Title: Some admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange OnlineUser impact: Admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange Online.
More info: While we work on developing a long-term solution, admins may use PowerShell for the affected migrations and moves with the following cmdlet against the affected mailboxes:
Set-MoveRequest “[email protected]” -SkipMoving FolderRestrictions
The tenant admin may then resume the move request (Resume-MoveRequest “[email protected]”) or simply resume the migration batch. This will allow the affected move jobs to continue to make progress.
Admins attempting to complete a tenant-to-tenant migration or an offboarding move in Exchange Online will be returned the following error “PropTagToPropertyDefinitionConversionException”
Current status: After analyzing backend settings and recent changes, we’ve isolated the offending change. This change introduced a code regression to Mailbox Replication Service (MRS), which causes intermittent failures for tenant-to-tenant migration actions or offboarding moves as the property tags needed to complete the request are not being properly configured. We’re creating and validating a code fix to address the regression and we aim to provide updates as development progresses. Simultaneously, we’ve expanded communications to all potentially affected tenants to ensure all affected admins are receiving updates about this issue.
Scope of impact: Some admins attempting to perform tenant to tenant migrations and offboarding moves in Exchange Online may be affected. This information may be updated as our investigation continues.
Root cause: A change introduced a code regression to Mailbox Replication Service (MRS), which causes intermittent failures for tenant-to-tenant migration actions or offboarding moves as the property tags needed to complete the request are not being properly configured.
Next update by: Friday, February 20, 2026, at 10:00 PM UTC
- 2026-02-15 01:47
Title: Some admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange OnlineUser impact: Admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange Online.
More info: While we work on developing a long-term solution, admins may use PowerShell for the affected migrations and moves with the following cmdlet against the affected mailboxes:
Set-MoveRequest “[email protected]” -SkipMoving FolderRestrictions
The tenant admin may then resume the move request (Resume-MoveRequest “[email protected]”) or simply resume the migration batch. This will allow the affected move jobs to continue to make progress.
Current status: We’ve been made aware of an issue in which some admins may be unable to perform tenant to tenant migrations and offboarding moves in Exchange Online. We’re reviewing backend settings and recent changes to identify the root cause and develop a long-term solution. In the meantime, admins can follow the steps listed in the More Info section of this communication to bypass the impact scenario.
Scope of impact: Some admins attempting to perform tenant to tenant migrations and offboarding moves in Exchange Online may be affected. This information may be updated as our investigation continues.
Next update by: Tuesday, February 17, 2026, at 10:00 PM UTC
