title: SharePoint 2010-"Cannot connect to the configuration database"
body: <p>I have TFS 2012 which integrated with SharePoint service, recently I duplicated the same machine for testing, and modified some parameters on the testing machine to avoid conflict due to they are in the same networking. They works well.</p>
  
  <p>Today the production server's SharePoint site prompt "<code>Cannot connect to the configuration database</code>", but team foundation service works well, I doubt that something in the testing server cause this, and I shutdown testing server, the issue still exists.</p>
  
  <p>Before I have experience for this issue, most of them are related with SQL server instance configuration like this "<a href="https://mikessharepoint.wordpress.com/2011/11/22/cannot-connect-to-the-configuration-database-error-of-central-administration/" rel="nofollow noreferrer">https://mikessharepoint.wordpress.com/2011/11/22/cannot-connect-to-the-configuration-database-error-of-central-administration/</a>" or some authentications issue in the IIS application pool. </p>
  
  <p>and here is the error event from event viewer:
  "</p>
  
  <pre><code>Unknown SQL Exception 53 occurred. Additional error information from SQL Server is included below.
  A network-related or instance-specific error occurred while establishing a connection to SQL Server. The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server is configured to allow remote connections. (provider: Named Pipes Provider, error: 40 - Could not open a connection to SQL Server)
  </code></pre>
  
  <p>"</p>
  
  <p>I doubt that something (probably SQL server instance name) on production server change to testing servers by some action, but I don't know where and how. </p>
  
  <p>And I doubt that the new server cause the error, the reason is I find something incorrect in wss_config database of production server, the "ServerName" filed in table TimerJobHistory, some value are new server, some value are old server. But even I update all the value to old server and restarted the production server, it does not work.</p>
  
  <p>I check all things I can googled, but nothing works, is there anybody could provide any help on this, appreciate for any kindly help.</p>