Problem Description
Mailbox restore operations to Exchange Online may fail if the target mailbox does not exist or is not properly licensed in Microsoft 365.
Cause
The restore process requires a valid, provisioned mailbox in Microsoft 365. Failures typically occur because:
The mailbox has been deleted.
The mailbox is in the process of being moved.
The mailbox does not have an active Exchange Online license.
📝 Note
The backup service (Druva) cannot automatically recreate or provision mailboxes in Microsoft 365; this must be done manually by the administrator.
Traceback / Logs
Common error messages encountered include:
"Mailbox move in progress. Try again later. Cross Server access is not allowed."
"Mailbox doesn't have a valid license.
“The license is invalid for this mailbox."
Resolution Steps
Follow these steps to resolve the failure and successfully restore the data:
Confirm Mailbox Status: Verify that the target mailbox exists in Microsoft 365.
Recreate Mailbox (If Needed): If the mailbox does not exist, manually recreate the user account and mailbox in Microsoft 365.
Assign License: Assign a valid and active Exchange Online license to the mailbox.
Wait for Provisioning: Wait until the mailbox is fully provisioned and accessible.
Verify User in Druva: Ensure the user is added and active in the backup service configuration (Druva).
Retry Restore: Retry the restore operation from the backup service to the newly created/verified mailbox.
Monitor: Monitor the restore process for any further errors and confirm successful data restoration.
📝 Important Note
A valid, provisioned, and licensed mailbox is non-negotiable as the restore destination. Attempting to restore to a non-existent or unlicensed mailbox will always result in failure. Always verify mailbox readiness before initiating a restore.