Published on

May 10, 2009

Common Connection Errors in SQL Server and How to Resolve Them

As a SQL Server user, you may have encountered connection errors while trying to establish a connection to the server. These errors can be frustrating and time-consuming to troubleshoot. In this article, we will discuss some of the common connection errors in SQL Server and provide step-by-step solutions to resolve them.

Error: 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)

This error typically occurs when the SQL Server service is not running or installed. To resolve this error, follow these steps:

  1. Ensure that the SQL Server service is running. Go to All Programs > Microsoft SQL Server > Configuration Tools > SQL Server Configuration Manager > SQL Server Services, and check if the SQL Server service status is “Running”.
  2. Verify that your remote server is in the same network. Run “sqlcmd -L” in your command prompt to see if your server is included in the network list.

Error: 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)

This error is similar to the previous one and can be resolved using the same steps mentioned above.

Error: Could not open a connection to SQL Server. (Microsoft SQL Server, Error: 1326)

This error occurs when the TCP/IP protocol is not enabled in SQL Server Configuration. To enable TCP/IP, follow these steps:

  1. Go to All Programs > Microsoft SQL Server > Configuration Tools > SQL Server Configuration Manager > SQL Server Network Configuration.
  2. Select TCP/IP, right-click, and click on Enable.
  3. Restart the SQL Server services for the changes to take effect.

Error: SQL Server ports are not open in the firewall

Windows Firewall can block SQL Server ports by default, preventing remote connections. To open the necessary ports, follow these steps:

  1. Go to Control Panel > Windows Firewall > Change Settings > Exceptions > Add Port.
  2. In the “Add a Port” popup, enter the following details:
    • Name: SQL
    • Port Number: 1433
    • Protocol: TCP

Error: Remote connections are not allowed

By default, remote connections are enabled in SQL Server 2008. However, if this feature is turned off, you need to enable it. Follow these steps:

  1. Right-click on the server node and select Properties.
  2. Go to the Connections tab and check “Allow remote connections to this server”.

Error: SQL Server Browser service is not enabled

If you have installed SQL Server as a named instance or if there is no specific TCP/IP port configured, you may encounter this error. To enable the SQL Server Browser service, follow these steps:

  1. Go to All Programs > Microsoft SQL Server > Configuration Tools > SQL Server Configuration Manager > SQL Server Browser.
  2. Right-click on SQL Server Browser and click on Enable.

Error: sqlbrowser.exe is blocked by the firewall

If the sqlbrowser service is not allowed to execute by the Windows Firewall, you need to create an exception for it. Follow these steps:

  1. Search for sqlbrowser.exe on your local drive where SQL Server is installed.
  2. Copy the path of the sqlbrowser.exe file.
  3. Create an exception for the sqlbrowser.exe file in the Windows Firewall settings.

Error: Alias needs to be recreated

Creating an alias for SQL Server can be useful when you need to move a physical SQL Server without changing any code or connection strings. If you encounter an error related to an alias, follow these steps:

  1. Go to All Programs > Microsoft SQL Server > Configuration Tools > SQL Native Client 10.0 Configuration > Aliases.
  2. Delete the problematic alias and recreate it with the same parameters.

We hope that this article has provided you with a comprehensive guide to resolving common connection errors in SQL Server. By following these steps, you can save time and frustration when troubleshooting connection issues. If you have any additional methods for fixing these errors, please leave a comment below.

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