Move on-premises mailboxes to Exchange Online

[AtanasM]

Cutover migration in Exchange Admin Center does not work. The migration batch fails maybe because the users are created already as Online users as well and are assigned Business Premium licenses.
They use only Teams Online, but Exchange Online licenses are not assigned, so there are no available Exchange Online mailboxes.
Error message after running the migration: "UnexpectedTargetRecipientTypeException: An unexpected recipient of the type "Mailuser" already exists in the target environment. A recipient of the type "Mailbox" was expected."

How can I perform now a migration?

[#2]

Any particular reason for choosing cutover? Hybrid/minimal hybrid will offer better experience, both on admin and end-user side.
But yes, the cutover process creates the users itself, and will fail if a user is already created. That's the reason why you cannot have dirsync enabled before doing cutover.

[#3]

I would like to avoid hybrid for now. What if I create Exchange Online mailboxes and perform PST migration?

[#4]

Hi Vasil Michev
do you have any answer of my question above?

[#5 · Accepted solution]

As long as you are OK with the PST ingestion process, sure.