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[Solved] AADSync – AADConnect : Unable to use MigrationWiz for migrations to Office 365

This week I had to migrate a customer, to Office 365.

This custom had already a connection to Office 365 for using Skype for Business.

Therefor they already had installed Azure AD Connect \ Azure AD Sync.

Because of the large mailboxes we decided to use MigrationWiz as the migration tool.

Unfortunately, you’re not able to use MigrationWiz, when AADConnect \ AADSync is used.

This is because of the msExchangeMailboxGuid attribute. This attribute syncs the local msExchangeMailboxGuid to Office 365, and therefor MigrationWiz is not able to create online Mailboxes.

Here the solution:

Start the Synchronization Rules Editor as an Administrator !

Under Inbound Rule types select ‘In from AD – User Exchange

Under Transformations select msExchMailboxGuid

Change the Flowtype to Expression

Change the Source to NULL

Check ‘Apply Once’ and press Update

Run a FULL (initial) Sync now !

From this moment you’re able to use MigrationWiz to create new Mailboxes in Office 365!