Article ID: 839269 - View products that this article applies to.
You may not be able to connect to an instance of SQL Server, and you may receive one of the following error messages.
Error message 1
[Named Pipes]SQL Server does not exist or access denied.
[Named Pipes]ConnectionOpen (Connect()).
Error message 2
Unable to connect to server <SQL Server instance name>
Server: Msg 17, Level 16, State 1
[Microsoft][ODBC SQL Server Driver][Named Pipes]SQL Server does not exist or access denied.
Error message 3
This behavior occurs when you do one of the following:
Cannot connect to <SQL Server instance name>
By default, Windows Firewall is enabled on computers that are running Microsoft Windows XP Service Pack 2. Windows Firewall closes ports such as 445 that are used for file and printer sharing to prevent Internet computers from connecting to file and print shares on your computer.
When SQL Server is configured to listen for incoming client connections by using named pipes over a NetBIOS session, SQL Server communicates over TCP port 445, just like file and printer sharing. Therefore, the SQL Server clients that are trying to connect to SQL Server receive the error messages that are mentioned in the "Symptoms" section.
To resolve this problem, you must enable the TCP port 445 explicitly. To do this, use one of the following methods.
To work around this problem, you can use the TCP/IP sockets network library. You can create an alias for the computer that is running SQL Server that uses the TCP/IP Sockets library or you can use TCP/IP as the only default enabled protocol. To add a SQL Server alias that uses TCP/IP Sockets library, follow these steps:
For additional information about Internet firewalls, click the following article numbers to view the articles in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/298804/ )Internet firewalls can prevent browsing and file sharing
(http://support.microsoft.com/kb/308127/ )How to manually open ports in Internet Connection Firewall in Windows XP
For additional information about other general causes of the error messages, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/328306/ )Potential causes of the "SQL Server Does Not Exist or Access Denied" error message
For additional information about configuring SQL Server 2000 and Windows XP Service Pack 2, click the following article number to view the article in the Microsoft Knowledge Base:
(http://support.microsoft.com/kb/841249/ )How to configure Windows XP Service Pack 2 (S) for use with SQL Server
Article ID: 839269 - Last Review: December 9, 2005 - Revision: 4.3
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