SQL Physical Connection is not usable

.net entity-framework entity-framework-6 sql-server sql-server-2014


I'm attempting to update my EF model after moving my application to a new DEV SQL Server. The database can connect using Management Studio 2014 (though truthfully, the connection has had some interruptions today). To update my EF model, I'm adding 2 tables using the "Update Model From Database" option (so obviously not using code first here). I experience a bug:

SQLException: A transport-level error has occurred when receiving results from the server. (provider: Session Provider, error: 19 - Physical connection is not usable).

On the initial screen, mistakes occasionally occur (Reading database information, please wait..., and times out). Sometimes I can complete the Update Wizard in its entirety and click Finish before running into the issue. The most of these's issues have happened during runtime, and I haven't discovered anything specifically to address this issue at design time... Any thoughts? Maybe I need a database permission?

4/2/2015 5:12:37 PM

Popular Answer

You say that "the connection has seen some hiccups today", which means that there's a problem between your client and the SQL box. Before attempting to work on your model, I'd concentrate on fixing those problems.

The error mentioned above typically denotes a connection issue with the database server.

I take it that the Dev SQL Server is powered by the Windows Server operating system? If not, you might be hitting the restrictions placed on the number of inbound TCP connections that can be made simultaneously on desktop versions of Windows. If you are one of several developers attempting to connect to the Dev SQL box, this is frequently made worse.

Other causes for this problem could be:

  1. erratic communication between your code and the SQL server. Verify the switches, cabling, etc.
  2. The SQL machine might not be trustworthy; look for unexpected reboots, HDD problems, etc. in the event log.
  3. While you were attempting to rejoin, the SQL machine may have been rebooted.
  4. Could your operations team have been performing maintenance on the SQL machine?
  5. Perhaps the SQL machine was doing updates?
  6. It might have been failing over if the machine is a SQL cluster (unlikely for Dev server).
4/2/2015 5:35:14 PM

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