Hello everyone! My client has a Hybrid environment, with some users that are synced with ADConnect, and others that are just Cloud users. Now all these users have to move to another tenant. How can I do this in the best way possible? I was thinking to migrate first the mailboxes from Exchange Online to Exchange ONPrem 2016, since the Hybrid is configurated. Than disconnect the ADconnect from the old Tenant, the synced users will now become just Cloud users, and can stay in the olt Tenant as Backup. At this point delete the Domains and add them in the new Tenant. Then install again the ADconnect and connect it to the new Tenant. After that disinstall and install again the HCW to connect the Exchange 2016 to the new Tenant. Can something go wrong?
You should be good, first off begin with patching your exchange server to latest CU to be able to leverage full power of hcw with auotomatic configuration of oauth, you will have to watch out for a few things:
In cloud user migration: To offboard in cloud users, there has to a corresponding remote mailbox on-premises with the same exchange guid as office 365 mailbox. So first you will have to get a remote mailbox provisioned on-premises with same exchange guid and make sure the objects sync.
Once offboarding is complete for all the users, you can disable dirsync, optionally clear out old target address (mail.onmicrosoft.com), remove connectors created by hybrid. Disable dirsync, free the domain add to target tenant and setup dirsync /hybrid.