Cause:

The error indicates that the specified folder (usually the primary mailbox) is missing or not accessible. Most often, this happens because the primary mailbox is not available for the affected user account.

error

 

Resolution:

 

For Exchange Server (On-Premises): kindly check the Primary Mailbox for the user via the Exchange Admin Center (EAC): Steps to check Primary  Mailbox in Exchange Admin Center (EAC).

 

1. Log in to the Exchange Admin Center (EAC).

2. In the left-hand navigation pane, go to Recipients.

3. Click on the Mailboxes tab.

4. Find and select the affected user from the mailbox list.


mailbox
 

5. Check the mailbox is available or not available.

For Microsoft 365: Steps to available Primary  Mailbox via Exchange Admin Center (EAC).

 

1. Log in to the Exchange Admin Center (EAC).

2. In the left-hand panel, go to Recipients.

3. Click the Mailboxes tab.

mailboxes tab
 

4. Find and select the user.

5. Check the mailbox is licensed or unlicensed.

Once the primary  mailbox is licensed, restart the migration process.