I receive this error when i'm trying to connect to my database project,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: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)
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Jignesh TrivediPosted Apr 15, 2014, 12:29 AM
I think this is same as
http://www.c-sharpcorner.com/Forums/Thread/252455/i-cannot-connect-to-my-database-projectnorthwind-database.aspx
Try following....
Go to
Configuration Tools > SQL Server Surface Area Configuration
Click on Surface Area Configuration for Services and Connections
Select the instance that is having a problem > Database Engine > Remote Connections
Enable local and remote connections
Restart SQL server instance
also refer for more help
http://blog.sqlauthority.com/2009/05/21/sql-server-fix-error-provider-named-pipes-provider-error-40-could-not-open-a-connection-to-sql-server-microsoft-sql-server-error/