This issue is related to your network / SQL Server / .NET.
The situation occurs when the connection between SQL Server and TM Master v2 has been closed.
The error message will be displayed if a connection is drawn from the connection pool and the connection to the server has been lost.
There is no way for a connection in the pool to know that the connection has been severed.
If the problem persists, please contact your IT department regarding the server and/or network.
You could suggest that they take a look at this article which explains possible causes for this error:
And this article, which explains the need for installing "Reliability Update 1 for the .NET Framework 4":
Download page for Microsoft .NET Framework 4 Reliability Update 1 (KB2533523)