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

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

Comments

• Anonymous
  July 23, 2007
  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.comsql_admin and setspn -A MSSQLSvc/Alpha:2450 microsfot.comsql_admin Also we have named SQLServer instance on this server [AlphaBeta] listening TCP port 2451 How correctly set SPN for [AlphaBeta]?

• Anonymous
  July 23, 2007
  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.

• Anonymous
  July 23, 2007
  Thanks a lot, Il-Sung. Dmitri.

• Anonymous
  September 28, 2007
  ...The service needed to be started from Surface config mgr.

• Anonymous
  October 03, 2007
  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.

• Anonymous
  November 15, 2007
  I added port 1443 to the IP all in configuration manager and started working

• Anonymous
  December 14, 2007
  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?

• Anonymous
  December 30, 2007
  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.

• Anonymous
  June 22, 2008
  Thank you very much for this article. Now everything works fine!

• Anonymous
  September 09, 2008
  Thanks for this.  You saved me a whole heap of pain.  Wish I'd read it yesterday.

• Anonymous
  November 04, 2008
  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

• Anonymous
  March 25, 2009
  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?

• Anonymous
  April 22, 2009
  Thanks very much for this. This is a perfect article. You saved so much time.

• Anonymous
  July 14, 2009
  Very helpful article - thank you for the gift!

• Anonymous
  July 18, 2009
  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

• Anonymous
  July 18, 2009
  Hi If you wants to know how to enable remote connections in sql server 2005 pls visit this http://aspnetmembershipprovider.blogspot.com/2009/02/eanble-remote-connections-on-instance.html Regards

• Anonymous
  July 21, 2009
  Hi !!! I am also facing the similar problem , actually i changed the port number in th Alias name for tcp which is different in the protocols for sqlexpress in  tcp. I think port number and name should be same and yours client must have calling same name which it wants to connect. Thanks

• Anonymous
  August 09, 2009
  I have sql server 2005 install in my laptop with window vista, i can't connect to database engine.

• Anonymous
  August 10, 2009
  I'm getting this same error and we are not using a SQL 2005 server, but a SQL 2000 backend.  The error references "SQL Server 2005", but also "System lacked sufficient buffer space or because a queue was full".  It almost sounds like an IIS problem.

• Anonymous
  February 25, 2010
  hi there, I have a static IP and my sql server machine is connected to router.Router doesn't allow port forwarding for 1433 port.So i am using 27015( Half Life's) port no. I have setup my sql server to listen to port 27015 also created alias for that. When I try to connect from outside my router network it shows me this error "Provide:TCP provide ,error:0,No connection could be made because the target machine actively refused it" Please guide me to solve the problem. Thanx in advance. Best Regards Hakim

• Anonymous
  December 20, 2011
  The TCP Port All did the trick! Thank you, Diogo Moura

• Anonymous
  January 11, 2012
  thank you very much for this, the IPALL port no. was the trick for me.

• Anonymous
  May 28, 2012
  I was receiving 10061 error because I changed my domain password (required by IT department), and did not update the properties of the SQL server instance. Solution in my case was to open Computer Management -> Services -> SQL Server [name] -> Properties, go to Log On tab, and update the password. I hope this helps someone.

• Anonymous
  January 31, 2013
  revisar que si esten arriba los servicios con services.msc en ejecutar... y hay buuscar servicios sql y darle iniciar a los dos servicios.. aclaro para el error 10061... a mi me funciono

• Anonymous
  October 09, 2013
  Nice trouble shoot. I was struggling w/ a new machine and i was sure it was the firewall. It was also set up to have an instance name. It would have been a while before i checked that. Nice job. Thanks. greg

• Anonymous
  April 03, 2015
  The comment has been removed