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Aug 25, 2005 | Home > Bugzero > FAQs > Errors

SQL Server JDBC Connection Errors: Error establishing socket, connection refused...

java.sql.SQLException: [Microsoft][SQLServer 2000 Driver for JDBC]Error establishing socket.
        at com.microsoft.jdbc.base.BaseExceptions.createException(Unknown Source)
        at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
        at com.microsoft.jdbc.base.BaseExceptions.getException(Unknown Source)
        at com.microsoft.jdbc.sqlserver.tds.TDSConnection.(Unknown Source)
        at com.microsoft.jdbc.sqlserver.SQLServerImplConnection.open(Unknown Source)
        at com.microsoft.jdbc.base.BaseConnection.getNewImplConnection(Unknown Source)
        at com.microsoft.jdbc.base.BaseConnection.open(Unknown Source)
        at com.microsoft.jdbc.base.BaseDriver.connect(Unknown Source)

SQL server 2005 JDBC Driver:
com.microsoft.sqlserver.jdbc.SQLServerException: The TCP/IP connection to the host has failed. 
                                     java.net.ConnectionException: Connection refused: connect
        at com.microsoft.sqlserver.jdbc.SQLServerException.makeFromDriverError(Unknown Source)
        at com.microsoft.sqlserver.jdbc.SQLServerException.connect(Unknown Source)
        at com.microsoft.sqlserver.jdbc.SQLServerDriver.connect(Unknown Source)

For this kind of database connection problem, there are always two distinct issues:
  1. The SQL server itself is not running or TCP/IP is disabled. That can be confirmed by run


    and see it is listed there. And then run

    telnet localhost 1433

    and see it can connect (or whatever port number).

  2. Even if the server is running, a client program such like jdbc may still fail to connect to it because of a


    For testing, you can turn off the XP firewall. And if you have other firewall running, check the firewall log and see any activities that might be related.

You can also verify whether or not your server is running from the

    SQL Server Network Utility

    on the server, or from another client utility such as

    SQL Query Analyzer

    or a command line utility such as


To check the enabled protocols for a server, follow these steps:
  1. In SQL Server 2000, start the SQL Server Network Utility (svrnetcn.exe).
  2. On the General tab, select the instance of Microsoft SQL Server on which to load an installed server network library.
  3. Make sure that TCP/IP appears in the Enabled Protocols list.
  4. To find the port number, in the Enabled Protocols list, click TCP/IP, and then click Properties. The Properties dialog box displays the port number.
There is an known bug: SQL Server May Not Listen on TCP/IP Sockets When TCP/IP is the Only Protocol

In a SQL Server 2000 custom installation, if TCP/IP is the only selected protocol and all other protocols are disabled, SQL Server may not initialize and listen on TCP/IP sockets. The Server Network Utility shows that it is listening only on TCP/IP port 1433 even though it is not. To identify if SQL Server is not listening on TCP/IP, check to see if the value for TcpPort in the following registry key is incorrectly set to blank or empty:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\ [Instance Name]\MSSQLServer\SuperSocketNetLib\Tcp\REG_SZ TcpPort=

To work around this problem, follow these steps:

  1. Start Registry Editor (Regedt32.exe).
  2. Locate the TcpPort value in the following key in the registry:

    Named instance:
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\[InstanceName]\MSSQLServer\SuperSocketNetLib\Tcp\TcpPort

    Default instance:

  3. . On the Edit menu, click String. Enter either of the following values:
    a. Type the port number you want. -or-
    b. Enter a value of 0 to have SQL Server dynamically detect and assign a port the next time SQL Server starts.

  4. Click OK.
  5. Quit Registry Editor.

SQL Server 2000 Service Pack 4 (SP4):

You are running a version of Microsoft SQL Server 2000 or Microsoft SQL Server 2000 Desktop Engine (also called MSDE) that has known security vulnerabilities when used in conjunction with the Microsoft Windows Server 2003 family. To reduce your computer's vulnerability to certain virus attacks, the TCP/IP and UDP network ports of Microsoft SQL Server 2000, MSDE, or both have been disabled. To enable these ports, you must install SQL Server 2000 Service Pack 3a, or the most recent service pack for Microsoft SQL Server 2000 or MSDE from    http://www.microsoft.com/sql/downloads/2000/sp4.mspx.

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