UPDATE NOV 1, 2022: Cross-tenant mailbox migration is now generally available! See Cross-tenant User Data Migration is Now Generally Available for details.
Historically, wh...
Updated Jan 07, 2025
Version 10.0
Blog Post
Kunjal Amin , this one solved it for me:
Check in the Azure AD portal of the source tenant that the enterprise application used by the migration has been created and that required permissions on MS Graph and Exchange Online have been assigned:
- Open up Azure AD portal -> Azure AD -> Enterprise Applications
- You should see an application named something like [target tenant]_Friends_[source tenant][some number] - e.g. contoso_Friends_wingtip_2198
- Check that proper permissions are assigned to the enterprise application:
- Microsoft Graph: Read and Write directory data
- Office 365 Exchange Online: Move mailboxes between organizations
In general run the checks listed in the article (the above check is not included for some reason).
Apart from this obvious pitfalls are:
Ensure ALL X500 alias'es are copied from source mailboxes to target mailboxes. Copying the legacyExchangeDN won't cut it.
Ensure ALL mailbox users are added to your migration group.
Hope this helps.
Morten
Easy Office 365 Management: https://easy365manager.com
PS - Lessons learned: This article does NOT address how to handle Office 365 (unified) groups, Teams, SharePoint/OneDrive. Check the scope of this in the source tenant!