Troubleshoot Connectivity Issue in SQL Server 2005 - Part III

Troubleshoot Connectivity Issue in SQL Server 2005 - Part III

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

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.

Error Message 3:

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: Shared Memory Provider, error: 40 - Could not open a connection to SQL Server)

Troubleshoot:
1) You might explicitly use "lpc:"prefix which ask for connect through shared memory. Either server instance was not started successfully or shared memory was not enabled on the server.To resolve this, you remove "lpc:"prefix in your connection string as long as Server is listening on other protocols or enable shared memory and restart server.

2) You explicitly use "lpc:"prefix and connect to a local named instance through form [./(local)/localhost/<machinename>]\<InstanceName>, but Sqlbrowser service was not started. To resolve this, you need to enable sqlbrowser.

3) You might connect through "lpc:" which not includes any server name, to fix this, add correct server name in your connection string.

Error Message 4:

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: TCP Provider, error: 0 - No connection could be made because the target machine actively refused it.)

Troubleshoot:
1) You might explicitly use "tcp:"prefix which ask for connect through TCP/IP, however either server was not listening on TCP/IP, to resolve this, either remove "tcp:"prefix in your connection string or enable tcp protocol.

2) You might not connect through the exact port that server is listening on, to verify this, go to SQL Configuration Managner
choose "Protocols for <InstanceName>" and click properties for TCP/IP, see which port is configured for server listening and then try connect through the port, like in connection string "tcp:<machinename>,<portnumber>".

3) The instance that you want to connect through TCP was not started, check server ERRORLOG and restart server.

Error Message 5:

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: SQL Network Interfaces, error: 26 - Error Locating Server/Instance Specified)

1) You might have named pipe or tcp enabled and connect to a named instance, but SQL Browser service was not started or enabled. To enable browser, First, Use net start or go to sql configuration manager(SSCM), check whether sqlbrowser service is running, if not, start it; Secondly,You still need to make sure SqlBrowser is active. Go to SSCM, click properties of sqlbrowser service -> Advanced-> Active “Yes” or “No”, if sqlbrowser is running but is not active, the service would not serve you correct pipe name and Tcp port info on which your connection depends.

Error Message 6:

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: SQL Network Interfaces, error: 41 - Cannot open a Shared Memory connection to a remote SQL server)

1) You might explicitly use "lpc:"prefix and connect to a named instance but specify FQDN/LoopbackIP/IP as <servername>, eg, your connection string looks like "lpc:<FQDN>\<InstnaceName>" or "lpc:127.0.0.1\<InstanceName>"..

2) You might explicitly use "lpc:"prefix and give the wrong server name in your connectionstring, eg: "lpc:xx" <xx> is not the hostname of your machine.

Error Message 7:

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: SQL Network Interfaces, error: 28 - Server doesn't support requested protocol)

1) You might explicitly use "np:" prefix in your connection string and try to connec to a named instance, but named pipe was not enabled on the remote server, to resolve this, enable the remote named pipe and restart instance or remove "np:"prefix if remote server is listening on TCP/IP.

2) You might explicitly use "tcp:" prefix in your connection string and try to connec to a named instance, but TCP/IP was not enabled on the remote server, to resolve this, enable the remote TCP/IP and restart instance or remove "tcp:"prefix if remote server is listening on Named Pipe.

Error Message 8:

An error has occurred while establishing a connection to the server. When connectiong 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:TCP Provider, errror:0-A connection attempt failed because the connected party did not properly respond after a period of time, or established connection failed because connected host has failed to respond.)

1) This is because connection blocked by Windows firewall. To resolve this, take follow steps:

a. Enable SqlBrowser, see the info in Message 4. Plus, add sqlbrowser.exe into Firewall exception list: HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\AuthorizedApplications\List
b. Add Tcp port to Firewall exception list. (eg, Name-1433:TCP, Value-1433:TCP:*:Enabled:Tcp 1433).
HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\SharedAccess\Parameters\FirewallPolicy\DomainProfile\GloballyOpenPorts\List.For more detailed operation, see http://support.microsoft.com/default.aspx?scid=kb;en-us;287932

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.

MING LU

SQL Server Protocols

Disclaimer: This posting is provided "AS IS" with no warranties, and confers no rights

 

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  • Please add 5 and 4 and type the answer here:
  • Post
  • I have a customer that is doing a client/server installation using existing SQL express installation.  On the server we have migrated the database and on the workstation we have tried to point to the server DB and get the error “server doesn't exist or access denied”.  I have tried to disable firewall on the server machine, same results.  I even did a full install on the client and tried to use the change database option.  It will see the remote server but when you hit “fetch DB from Server” it gives the same error.  The server is running windows server 2003 and the client machine is windows XP.  Do you have any suggestions on what I can try next?

    1. restarted the SQL browser

    2. made sure Listen all is enabled

    3.Client server in same network and domain

    4.Firewall is off, did it on both server and client to be sure

    5.Settings on SQL surface configuration is enabled except VIA

    Please help me in resolving this issue

    And log says:

    Opening of connection failed.Error no:--2147467259.Error description:-[Microsoft][ODBC SQL Server Driver][DBNETLIB]SQL Server does not exist or access denied.

  • We're sometimes getting this error, which doesn't seem to be covered by anything in this article:

    [SQL Native Client]TCP Provider: The semaphore timeout period has expired.

    [SQL Native Client]Communication link failure

    Any ideas?

  • Bad public user name or password. Database Server Error: SQL Network Interfaces: Error Locating Server/Instance Specified [xFFFFFFFF]. ;

    i have this error when trying to configur primavera database.Please help me!!!

  • I just encontered this problem and the way I resolved it was just restarting the PC after creating the new user.

  • I have a problem creating a communication between sqlserver and sqlclient,when running both sqls the sqlclient cannot see or recognise sqlserver.what might be the problem?

  • thanks. This worked for me.

    cheers

    Sathya

  • I have Server X (SQL2008 R2 RTM) and Server Y (SQL2008 R2 RTM) connected via a VPN.

    Server X has a linked server set up to Server Y and pulls data accross from Server Y on a regular basis. This works fine but sometime the following error is recieved on Server X:

    select top 1 * from ServerY.[DBName].dbo.Test

    OLE DB provider "SQLNCLI10" for linked server returned message "Communication link failure".

    Msg 64, Level 16, State 1, Line 0 TCP Provider: The specified network name is no longer available.

    We have created Linked server we don't find any issue in it we can browse the linked server node and can see all the objects in the database. Also i have create DSN and check it was working fine and no connection issue. Able to ping also network guys says there was no packet drops as well.But still when we query using linked server it gives error.

    Everytime i need to reboot the server and problem gets resolved Simply stopping and starting SQL does not fix it.

    Please help urgently

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