Let us examine the error 1433 SQL server not listening and the reasons and solutions for it with the support of our MSSQL support services at Bobcares.

Error: 1433 SQL server not listening

While configuring an ODBC connection from another machine, the error MS-SQL server does not respond may appear. We can go through some steps to answer and resolve this error.

Reason for the 1433 SQL Server Not Listening Error

There could be a number of reasons why we are unable to connect to the MS-SQL server, but there are two main ones:

• A local firewall prevents connections.
• The currently active communication port is not active.

Before we can begin troubleshooting the MS-SQL connection, we must first test the connection.

Test the MS-SQL connection

To test the connection, we can use the Telnet client program. Using the Telnet client program is quick and eliminates the need to repeatedly type the username and password during the test and subsequent troubleshooting.

The Telnet client is enabled by default on most Windows machines; however, the Telnet client might not be enabled by default on some Windows version Server machines.

To enable the Telnet client on Windows server machines

Follow the steps given below to manage the 1433 SQL server not listening error:

1. To open the Control Panel form on the local machine, go to Start then to Control Panel.
2. Click Programs and Features in the Control Panel form to open the Programs and Features form.
3. Click Turn Windows features on or off in the Programs and Features form to open the Windows features form.
4. Close the Windows features form by checking the Telnet Client box and clicking the OK button.
5. Close the Programs and Features and Control Panel windows.
6. Click the Start button on the local machine and type “CMD” into the search programs and files field.
7. Enter “Telnet IP-address 1433” in the Command Prompt.
8. If port 1433 is not open,  it will immediately return an error. We will be able to connect to the MS-SQL server if port 1433 is open.

To use the Telnet client to test a connection

Local Firewall on the MS-SQL server can block connection

If the Telnet client returns an error when testing the connection on port 1433, the connection to the MS-SQL server may be blocked by the local firewall. Temporarily disable the firewall on the MS-SQL server to see if it is blocking the connection.

If we can connect to the MS-SQL server while the firewall is turned off, we can create a firewall rule granting either local scope or specific IP addresses the right to do so and re-enable the firewall.

If we are unable to connect to the MS-SQL server when the firewall is disabled, it is possible that port 1433 is disabled. To test the connection, enable the firewall and open port 1433.

Port 1433 disabled on the MS-SQL Server

Port 1433 was enabled (open) by default in previous versions of MS-SQL server, but as part of a hardening procedure implemented to improve the security of the MS-SQL server, port 1433 is disabled in current versions of MS-SQL Server.

If a port is disabled, any communication requests made through that port are ignored by the local machine.

Enable port 1433 on the MS-SQL Server

On the MS-SQL server, we can enable port 1433 in two ways:

• Using SQL Server Configuration Manager
• Using the Windows Registry

To enable port 1433 on the MS-SQL Server through the SQL Server Configuration Manager

1. Open the SQL Server Configuration Manager1 by clicking Start > All Programs > MS-SQL Server 2008 R2> Configuration Tools > SQL Server Configuration Manager on the MS-SQL Server machine.
2. Click SQL Server Network Configuration > Protocols for SQLExpress in the left pane of the SQL Server Configuration Manager form.
3. To open the TCP/IP Properties form, right-click the TCP/IP field in the Protocol Name column in the right pane and select Properties.
4. Expand the IPALL group in the TCP/IP Properties form> IP addresses tab and enter “1433” in the TCP port field.
5. Close the TCP/IP Properties form and the SQL Server Configuration Manager form by clicking the OK button.

The following procedure is based on MS-SQL Express 2008 R2. Other MS-SQL versions may differ slightly.

To enable port 1433 on the MS-SQL Server through the Windows Registry¹

• To open the Registry Editor form on the local machine, click the Start button and type “Regedit” into the search programs and files field.
• Navigate to the HKEY LOCAL MACHINE SOFTWARE Microsoft SQL Server SQLEXPRESS MSSQLServer SuperSocketNetLib TCP folder in the Registry Editor form’s left pane.
• Close the Registry Editor form after changing the TcpPort registry key setting to 1433.

[Need assistance with similar queries? We are here to help]

Conclusion

To conclude the error 1433 SQL server, not listening can occur due to multiple reasons. Two reasons are more prevalent in generating the error. We can remove the error following simple troubleshooting steps from our MSSQL support services.