Troubleshooting Mirroring Configuration I am configuring database mirroring on SQL Server 2012.  After configuration I am getting the following error when attempting to start the mirroring session:

tcp server cannot be reached or does not exist.  Check the network address name and the ports for the local and remote are operational.
an Exception occured while executing a Transactional-SQL Statment.
You should check the error log on both Principal and Mirror server.

One common error is that you run your Database Engine Service with a different accounts on your servers, in that case your need to grant connect permissions to the accounts on respective endpoints. 

GRANT CONNECT ON ENDPOINT::Endpoint_Mirroring TO [Mydomain\username4service];
GO