When creating a new migration batch to move mailboxes from Exchange On-premises to Exchange Online, the following error occurs:
error: The connection to the server ‘mail.x500.co.uk’ could not be completed.
Mailbox moves were previously successful.
Investigation & Fix
Firstly identify the associated on-premises AD administrator account for the relevant Migration Endpoint.
In the Exchange admin center, click on recipients from the left menu bar, then the migration tab. Click on the three dots icon, then click Migration endpoints.
In this example there is only one Migration Endpoint, named MigrationEndpointV0. The associated administrator account is named MigrationEndpoint (X500\MigrationEndpoint).
Now check for the following in on-premises AD.
- does the account still exist – has it been deleted?
- is the account disabled?
- is the account locked out?
- has the password expired (if ‘password never expires’ is not set)
- has the account expired?
In this example, the cause is password expiry on the account.
If you’re not sure of what the password for the account is, reset it. Ensure ‘password never expires’ is set on the account to prevent a reoccurrence of this issue.
Update the Migration Endpoint (click Update).
Enter the new password, click Save.