Office 365, PowerShell, Technology

Exchange Online Migration error: “Target user already has a primary mailbox”

Issue When migrating mailboxes from Exchange On Premise to Exchange Online, it fails with the following error: Target user ‘Users Name’ already has a primary mailbox. Cause Long before we had ever thought about migrating to Exchange Online we had manually created some students in our Office 365 tenant (not using the Azure AD Connect) to give them access to…

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