Error Message

An error has occurred while establishing a connection to the server.
(provider: Named Pipes Provider, error: 40 – Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 5)

An error has occurred while establishing a connection to the server. When connecting to SQL Server 2005, this failure may be caused by the fact that under the default settings SQL Server does not allow remote connections. (provider: Named Pipes Provider, error: 40 – Could not open a connection to SQL Server) (Microsoft SQL Server, Error: 1326)

Solution

1) SQL Server should be up and running.
Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Server Configuration Manager >> SQL Server Services, and check if SQL Server service status is “Running”.
2) Enable TCP/IP in SQL Server Configuration
When two or more SQL Servers are connected across network they do all communication using TCP/IP. The default port of SQL Server installation is 1433. This port can be changed through SQL Server Configuration Manager. TCP/IP should be enabled for SQL Server to be connected.
Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Server Configuration Manager >> Select TCP/IP.


3) Right Click on TCP/IP >> Click on Enable


You must restart SQL Server Services for all the changes to take effect. Right click and go to menu properties to select location where default port of SQL Server can be changed.

4) Open Port in Windows Firewall
Go to Control Panel >> Windows Firewall >> Change Settings >> Exceptions  >> Add Port


5)Make the following entries in popup “Add a Port” and click OK.

Name : SQL
Port Number: 1433
Protocol: Select TCP

6) Enable Remote Connection
Go to Left Tab of Connections and check "Allow remote connections to this server"
Go to Left Tab of Connections and check "Allow remote connections to this server".
7) Enable SQL Server Browser Service
Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Server Configuration Manager >> SQL Server Browser
Right Click on SQL Server Browser >> Click on Enable
8) Create exception of sqlbrowser.exe in Firewall
Search for sqlbrowser.exe on your local drive where SQL Server is installed. Copy the path of the sqlbrowser.exe like C:\Program Files\Microsoft SQL Server\90\Shared\sqlbrowser.exe and create the exception of the file in Firewall, as delineated in Step 3.
9) Recreate Alias
Go to All Programs >> Microsoft SQL Server 2008 >> Configuration Tools >> SQL Native Client 10.0 Configuration >> Aliases

Conclusion

I tried to explain my best, if I missed anything. Please leave a comment.