provider: Named Pipes Provider, error: 40 – could not open a connection to SQL server.

问题

I developed a .net application that depends on a sql server database, the database was on the local machine used for development of the application.

When I moved the database to a remote machine and changed the connection string I got the following error:

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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 default settings SQL server does not allow remote connection. ( provider: Named Pipes Provider, error: 40 – could not open a connection to SQL server. )

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This error occurs only from XP machines but it works fine from Win. 7 Machines with the same connection string:

connectionString="Data Source=ot;Initial Catalog=sp_warehouse;User ID=fu;Password=bar"

I tried the following to troubleshoot the problem: - Disabled Named Pipes service from the server. - Added an exception in the server firewall for the SQL Server port 1433 - Disabled the firewall on the server completely - Added this parameter in the connection string: Network Library=DBMSSOCN;Persist Security Info=True

Each time I try something I get the same result, win. 7 machines work fine but XP machines don't.

Note: There's another application works from XP machines that uses another database on the same SQL Server and it's working fine.

回答1:

Make sure the SQL Browser is enabled and running on your remote machine. You'll probably want to leave named pipes enabled.

来源：https://stackoverflow.com/questions/6897272/provider-named-pipes-provider-error-40-could-not-open-a-connection-to-sql-s