Dot Net Tips and Tricks

Part III – Connection Fail when SqlClient connects to Sql Server 2005

I found this article for troubleshooting Service broker and thought others might find it useful. I’ve just posted the summary and the link to the original is below.

When you connect to SQL Server 2005 either using “SQL Server Managment Studio” or any application compiled with .NET Framework 2.0, you are using SqlClient provider(Access data from within a CLR database object by using the .NET Framework Data Provider for SQL Server.)

Error Message 1:

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)

Troubleshoot:
1) Make sure your sql service is running, use either “net start” or “sc query <InstanceName>” or run services.msc, check status of the server; If server start fail, go to ERRORLOG to see what happened there, fix the problem and restart server.

2) You might explicitly use “np:”prefix which ask for connect through named pipe. However, client can not connect to server through the pipe name that specified.Double check the server is started and listening on named pipe if you enabled Named Pipe. One way is that see the ERRORLOG of the server, search follow keywords:

Server named pipe provider is ready to accept connection on [ \\.\pipe\sql\query ] or [\\.\pipe\mssql$<InstanceName>\sql\query]

Notice that “sql\query” is the default pipe name, so you need to know server is listening on which pipe name. eg: if you specify server pipe name is “sql\query1″, then you would see in the errorlog that server listening on [ \\.\pipe\sql\query1 ], and go to SQL Server Configuration Manager, click client Named Pipe properties, see whether the pipe name is same with the one server listening on.

3) You might specify named pipe protocol in connection string, but did not enable named pipe on the server, check ERRORLOG.

4) You might use FQDN/IPAddress/LoopbackIP to connect to the server when only shared memory was enabled, you can change to <machinename> to resolve this.

5) You might explictly specify “lpc:” prefix in your connection string, but shared memory was not enabled. To resolve this, either remove the prefix as long as named pipe or tcp was enabled or enable shared memory.

Error Message 2:

A connection was successfully established with the server, but then an error occurred during the pre-login handshake. 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: 0 – No process is on the other end of the pipe.)

1) You might explicitly use “np:”prefix which ask for connect through named pipe and specify FQDN/LoopbackIP/IPAddress as server name in the connection string.
2) You might use FQDN/IPAddress/LoopbackIP to connect to the server.

To resolve 1) and 2), you can specify <machinename> instead of FQDN/IPADress/LoopbackIP.

More of the article…

Summary:

1) In any case, SqlClient should be able to connect to SQL Instance through any of the protocols(Shared Memory/Named Pipe/TCP) as long as SQL Instance was started successfully.

2) And if you speculate any protocol in connection string (“lpc:”/”np:”/”tcp:”), the error message would display “<Protocol> Provider, error <Num1> -….<Num2>.” <Protocol> stands for “Shared Memory” or “Named Pipes” or “TCP”; If you do not speculate
any protocol, the error message indicates that connection fails when connecting through specific <Protocol>.

3) In the error message format for SqlClient, please notice two different error number. <Num1> stands for internal error thrown out by SQL Protocols, <Num2> is the OS error(eg: 233 – No process is on the other end of pipe). When you see <Num1>=0, that means the connection fails due to OS error not caused by SQL Protocols, under this situation, you can use “net helpmsg” to check specific OS info.

Finally, if you were developing .NET framework application and came across above issues in your client app, the best way is first try SQL Server Management Studio to connect to SQL Server using the exact same connection string in your app, and watch the error message, normally, there is additional error info at the end of error string, eg ( Microsoft SQL Server, Error:87) which gives you clue(net helpmsg 87) that problem inside your connection string.

I found a nice trick for the Infragistic’s UltraWinGrid. The UltraGridRow has a property ListObject which can be cast to the original datasource object.  An example would be the following:

IList<CustObjectBE> orders = new List<CustObjectBE>();

UltraWinGrid grid = gridOrders; <– Grid on a form.

grid.DataSource = orders;

UltraGridRow row = grid.ActiveRow;

CustObjectBE order = row.ListObject as CustObjectBE;

if (order != null)

{

//Do something here.

}

This method provides a convenient way to get the bound object to a row in the grid.