Scenario:
A Hybrid Exchange Environment is in place and you are having problems migrating a mailbox from Exchange Online (Office 365 Email) back to Exchange on premises.

Symptoms:
When you attempt to off board the user, the move request takes an unusual amount of time to validate. Once it finally validates, the move request is generated but the request gets stuck at 0% and shows a StatusDetail of “RequestExpiryCleanup”.

Things You’ve Already Tried:
You have attempted to remove the move request and have created a new off boarding request a few times. However, the problem still persists.

Solution:
Do a targetless move request from within Exchange Online. This will move the mailbox into a different database within Exchange Online. Here’s how:

1. Connect to Exchange Online PowerShell

2. Remove the problematic move request and migration user:

Remove-MigrationUser -Identity stuckuser@contoso.com
Remove-MoveRequest -Identity stuckuser@contoso.com

3. Perform the targetless move request (move the mailbox to a new DB in EXO)

New-MoveRequest -Identity stuckuser@contoso.com

4. Monitor the move request, until completion:

Get-MoveRequestStatistics -Identity stuckuser@contoso.com

Once the new move request finishes, go back into the Exchange Admin Center via the O365 portal (or use PowerShell) and generate a new off boarding request.

Hope this helps!