Microsoft Exchange Error in moving user mailboxes

I tried to remove my old server and tried to move my user mailboxes to the new server only to be greeted with the error saying,

I tried to remove my old server and tried to move my user mailboxes to the new server only to be greeted with the error saying,
In order to see these arbitration mailboxes in your database use the command:
Hello Hannah,
This error appears when you try to remove the Exchange Server 2010 from the environment then this error shows at least one time. To solve this issue you should remove the chat server hosted databases along with the Exchange server 2010. The exchange server does not allow the user to remove the server if there are mailboxes present. Now to remove the error successfully, please follow the steps given below:
1- Please move all of your mail boxes to any other database or simply just remove them if you do not need them.
2- Now Run the following command: Get-Mailbox –Database DB001 –Arbitration | Remove-Mailbox –RemoveLastArbitrationMailboxAllowed:$True . This command is used for the removal of arbitration mailboxes.
This will work for you.
Thanks