Error: Database cannot be opened. It is in the middle of a restore

This may be a bug in SSMS, after restoring FULL and LOG backups when we start mirroring we get this error - To solve execute bellow commands so that mirroring will start - 

First In Mirror instance:

ALTER DATABASE DBNAME
    SET PARTNER =   
    'TCP://PRINCIPAL SERVER.DOMAIN:MIRRORING PORT NUMBER'  
 

In Principal instance:

ALTER DATABASE DBNAME
    SET PARTNER =   
    'TCP://MIRRIR SERVER.DOMAIN:MIRRORING PORT NUMBER'