TCP Provider: No connection could be made because the target machine actively refused it

TCP Provider: No connection could be made because the target machine actively refused it

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In this post, I am trying to list out potential cause and general solution to this specific error when you are making connection to SQL Server 2005.

First, It is due to TCP connection fail, since you can tell from the title, "TCP Provider: .xx", which indicates that either your connection string explicitly use 'tcp:" prefix, say "Server=tcp:<machinename> ...." or your client protocol setting ask for first try Named Pipe connection, if fails, then fallback to TCP connection. For eg, in "Client NetworkUtility", you see the protocol order is "np on top of tcp". 

Secondly, this error is winsock error "WSAECONNREFUSED  - 10061". You'd better go through the following checklist to fix the "connection refused" problem.

1) Are you connecting to the right server? Check out whether your target machine name is valid.

2) Whether the <machinename> you specified in your connection string resolve to the correct ipaddress? do:

  ping <machinename> (if your remote server has ipv6 enabled, it might return ipv6 address). Go to the remote machine to see whether it returned the correct ipaddress.

 Then do ping -a <ipaddress>, can it be resolved to correct target machine name?

3) Are you connecting to default instance or named instance? Please go to the target machine, to check whether the instance started successfully, you can go to "Service Control Manager", find out "MSSQLSERVER" or "MSSQL$<instancename>" whether they are running?

4) Does your target SQL instance enabled TCP and listening on a valid TCP port?

a. If it is default instance, on your client machine, try : "telnet <ipaddress> 1433", remember, SQL Server 2005 default instance always use the reserved port 1433, namely, if you modify it to any other port number, the client app can not connect to the sql instance.

b. If it is named instance, on your target server machine, go to "SQL Server Configuration Manager", open "Protocols for MSSQL$<instancename>", check TCP enabled, and right click TCP, find out the tcp port number under 'IPAll". Then on your client machine, do " telnet <hostname> <portnumber>", see whether it succeeds.

5) Is your browser service running on the target server?

If you connect to named instance, then on your target server machine do "net start sqlbrowser".

6) Are your target server behind firewall?

If so, go to " SQL Server 2005 Surface Area configuration", click "Surface Area configuration for service and connection", then click the instance name, enable its remote connection.

You should be able to see the sql tcp port and udp port(1434 for browser service) is opened in Firewall, which enable you can telnet from client.

7) Does your client app set any alias that cause the connection redirect to an invalid port?

a. If you are using MDAC: on your client machine, click "cliconfig.exe", check out alias, whether it points to some other port that you can not telnet, if so, correct it or remove alias, since you should be able to connect through servername by sqlbrowser service automatcally respond to the correct port which server is listening on.

b. If you are using SNAC/SqlClient,  go to SQL Configuration Manager, check out client protocols, see alias setting.

8) Check out IPSec setting if you still face problem. See whether IPSec specification make dropping any packets.

9) If you still face problem, please use "Evenvwr" on the client machine, try to look up the remote server application log, see any info from SQL Server that indicates the sql instance reject client connection. Under this situation, it probably due to invalid client request. Open SQL Profile also can help you dig out which client data operation make server terminate the connection.

MING LU

SQL Server Protocols

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

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  • Hello,

    could explain how correctly set SPNs for many instances, i.g.

    fot default instance of sqlserver Alpha.microsfot.com we have:

    setspn -A MSSQLSvc/Alpha.microsfot.com:2450 microsfot.com\sql_admin

    and

    setspn -A MSSQLSvc/Alpha:2450 microsfot.com\sql_admin

    Also we have named SQLServer instance on this server [Alpha\Beta] listening TCP port 2451

    How correctly set SPN for [Alpha\Beta]?

  • Hi Dmitri,

    For your Beta instance, you would use:

    setspn -a MSSQLSvc/Alpha.microsoft.com:2451 <service account>

    i.e, specify the port upon which the instance listens.

    Il-Sung.

  • Thanks a lot, Il-Sung.

    Dmitri.

  • ...The service needed to be started from Surface config mgr.

  • I'm getting this error using 2005 Analysis Server, when it tries to connect to localhost. localhost is started and I'm using the MS OLE data provider for Analy Server 2005. Some assistance please.

  • I added port 1443 to the IP all in configuration manager and started working

  • What are ways to trace why a connection is falling back to named pipes from TCP in SQL 2005, with a 3rd party app using MDAC connection?

  • hi

    please see this link.

    http://forums.microsoft.com/msdn/ShowPost.aspx?postid=2599765&isthread=true&siteid=1&authhash=e32f034172355a7d495a3cac5f97787d281f0964&ticks=633343088547298394

    email:Bahmanymb@gmail.com

    thanks.

  • Thank you very much for this article. Now everything works fine!

  • Thanks for this.  You saved me a whole heap of pain.  Wish I'd read it yesterday.

  • ok i have went through all the step that you have here and read all the blogs that are up and My error is still occuring. I

    TCP Provider, error: 0 - No connection could be made because the target machine actively refused itf anyone could help please

    i read the blog that states that i should check this and that but the thing is that i have more apps going to through the firewall and remotey connectin. only thing  different with my app is that i am using a Sqldatasource connection and in the web.config it add another name than what what was there. Cause it is another connection to the database. please and sorry so long

  • In Step 4 it reads: "if you modify it to any other port number, the client app can not connect to the sql instance"

    Are you telling me that you simply cannot remotely connect to a default instance using a non standard port?

  • Thanks very much for this. This is a perfect article. You saved so much time.

  • Very helpful article - thank you for the gift!

  • Hi

    i was facing the error when opening connection using sqlconnection

    nw got solved

    http://sqlservererror-info.blogspot.com/2009/07/error-has-occurred-while-establishing.html

    http://aspnetmembershipprovider.blogspot.com/2009/02/error-has-occurred-while-establishing.html

    See This

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