No connection could be made because the target machine actively refused it?

Sometimes I get the following error while I was doing HttpWebRequest to a WebService. I copied my code below too.

System.Net.WebException: Unable to connect to the remote server ---> System.Net.Sockets.SocketException: No connection could be made because the target machine actively refused it
   at System.Net.Sockets.Socket.DoConnect(EndPoint endPointSnapshot, SocketAddress socketAddress)
   at System.Net.Sockets.Socket.InternalConnect(EndPoint remoteEP)
   at System.Net.ServicePoint.ConnectSocketInternal(Boolean connectFailure, Socket s4, Socket s6, Socket& socket, IPAddress& address, ConnectSocketState state, IAsyncResult asyncResult, Int32 timeout, Exception& exception)
   --- End of inner exception stack trace ---
   at System.Net.HttpWebRequest.GetRequestStream()

ServicePointManager.CertificatePolicy = new TrustAllCertificatePolicy();
HttpWebRequest request = (HttpWebRequest)WebRequest.Create(url);

request.PreAuthenticate = true;
request.Credentials = networkCredential(sla);
request.Method = WebRequestMethods.Http.Post;
request.ContentType = "application/x-www-form-urlencoded";
request.Timeout = v_Timeout * 1000;

if (url.IndexOf("asmx") > 0 && parStartIndex > 0)
    AppHelper.Logger.Append("#############" + sla.ServiceName);

    using (StreamWriter reqWriter = new StreamWriter(request.GetRequestStream()))
        while (true)
            int index01 = parList.Length;
            int index02 = parList.IndexOf("=");

            if (parList.IndexOf("&") > 0)
                index01 = parList.IndexOf("&");

            string parName = parList.Substring(0, index02);
            string parValue = parList.Substring(index02 + 1, index01 - index02 - 1);

            reqWriter.Write("{0}={1}", HttpUtility.UrlEncode(parName), HttpUtility.UrlEncode(parValue));

             if (index01 == parList.Length)

             parList = parList.Substring(index01 + 1);
     request.ContentLength = 0;

 response = (HttpWebResponse)request.GetResponse();

28 Answers

If this happens always, it literally means that the machine exists but that it has no services listening on the specified port, or there is a firewall stopping you.

If it happens occasionally – you used the word “sometimes” – and retrying succeeds, it is likely because the server has a full ‘backlog’.

When you are waiting to be accepted on a listening socket, you are placed in a backlog. This backlog is finite and quite short – values of 1, 2 or 3 are not unusual – and so the OS might be unable to queue your request for the ‘accept’ to consume.

The backlog is a parameter on the listen function – all languages and platforms have basically the same API in this regard, even the C# one. This parameter is often configurable if you control the server, and is likely read from some settings file or the registry. Investigate how to configure your server.

If you wrote the server, you might have heavy processing in the accept of your socket, and this can be better moved to a separate worker-thread so your accept is always ready to receive connections. There are various architecture choices you can explore that mitigate queuing up clients and processing them sequentially.

Regardless of whether you can increase the server backlog, you do need retry logic in your client code to cope with this issue – as even with a long backlog the server might be receiving lots of other requests on that port at that time.

There is a rare possibility where a NAT router would give this error should its ports for mappings be exhausted. I think we can discard this possibility as too much of a long shot though, since the router has 64K simultaneous connections to the same destination address/port before exhaustion.

The most probable reason is a Firewall.

This article contains a set of reasons, which may be useful to you.

From the article, possible reasons could be:

  • FTP server settings
  • Software/Personal Firewall Settings
  • Multiple Software/Personal Firewalls
  • Anti-virus Software
  • LSP Layer
  • Router Firmware
  • Computer Turned Off
  • Computer Not Plugged In
  • Fiddler

This happened to me too.. Sometimes when I open my project this error shown up which was frustrating. The problem was that sometimes the port-number of web service was changing unexpectedly.

This problem usually happens when you have more than one copies of the project

My project was calling the Web service with a specific port number which I assigned in the Web.Config file of my main project file. As the port number changed unexpectedly, the browser was unable to find the Web service and throwing that error.

I solved this by following the below steps: (Visual Studio 2010)

Go to Properties of the Web service project --> click on Web tab --> In Servers section --> Check Specific port and then assign the standard port number by which your main project is calling the web service.

I hope this will solve the problem.

Cheers 🙂

I think, you need to check your proxy settings in “internet options”. If you are using proxy/’hide ip’ applications, this problem may be occurs.

I had the same problem. The problem is that I didn’t start the selenium server. I have downloaded the selenium server and i started it. After starting the selenium server, issue gone and all worked fine.

Refer this :

I had the same error with my WCF service using Net TCP binding, but resolved after starting the below services in my case.



Net.Tcp Port Sharing Service

I faced same error because when your Server and Client run on same machine the Client need server local ip address not Public ip address to communicate with server you need Public ip address only in case when Server and Client run on separate machine so use Local ip address in client program to connect with server Local ip address can be found using this method.

 public static string Getlocalip()
            IPAddress[] localIPs = Dns.GetHostAddresses(Dns.GetHostName());
            return localIPs[7].ToString();
        catch (Exception)

            return "null";


I got this error in an application that uses AppFabric. The clue was getting a DataCacheException in the stack trace. To see if this is the issue for you, run the following PowerShell command:

@("AppFabricCachingService","RemoteRegistry") | % { get-service $_ }

If either of these two services are stopped, then you will get this error.

Well, I’ve received this error today on Windows 8 64-bit out of the blue, for the first time, and it turns out my my.ini had been reset, and the bin/mysqld file had been deleted, among other items in the "Program Files/MySQL/MySQL Server 5.6" folder.

To fix it, I had to run the MySQL installer again, installing only the server, and copy a recent version of the my.ini file from "ProgramData/MySQL/MySQL Server 5.6", named my_2014-03-28T15-51-20.ini in my case (don’t know how or why that got copied there so recently) back into "Program Files/MySQL/MySQL Server 5.6".

The only change to the system since MySQL worked was the installation of Native Instruments’ Traktor 2 and a Traktor Audio 2 sound card, which really shouldn’t have caused this problem, and no one else has used the system besides me. If anyone has a clue, it would be kind of you to comment to prevent this for me and anyone else who has encountered this.

For service reference within a solution.

  1. Restart your workstation

  2. Rebuild your solution

  3. Update service reference in WCFclient project

At this point, I received messsage (Windows 7) to allow system access. Then the service reference was updated properly without errors.

I would like to share this answer I found because the cause of the problem was not the firewall or the process not listening correctly, it was the code sample provided from Microsoft that I used.

I implemented this function almost exactly as written, but what happened is I got this error:

2016-01-05 12:00:48,075 [10] ERROR – The error is: System.Net.Sockets.SocketException (0x80004005): No connection could be made because the target machine actively refused it [fe80::caa:745:a1da:e6f1%11]:4080

This code would say the socket is connected, but not under the correct IP address actually needed for proper communication. (Provided by Microsoft)

private static Socket ConnectSocket(string server, int port)
        Socket s = null;
        IPHostEntry hostEntry = null;

        // Get host related information.
        hostEntry = Dns.GetHostEntry(server);

        // Loop through the AddressList to obtain the supported AddressFamily. This is to avoid
        // an exception that occurs when the host IP Address is not compatible with the address family
        // (typical in the IPv6 case).
        foreach(IPAddress address in hostEntry.AddressList)
            IPEndPoint ipe = new IPEndPoint(address, port);
            Socket tempSocket = 
                new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);


                s = tempSocket;
        return s;

I re-wrote the code to just use the first valid IP it finds. I am only concerned with IPV4 using this, but it works with localhost,, and the actually IP address of you network card, where the example provided by Microsoft failed!

    private Socket ConnectSocket(string server, int port)
        Socket s = null;

            // Get host related information.
            IPAddress[] ips;
            ips = Dns.GetHostAddresses(server);

            Socket tempSocket = null;
            IPEndPoint ipe = null;

            ipe = new IPEndPoint((IPAddress)ips.GetValue(0), port);
            tempSocket = new Socket(ipe.AddressFamily, SocketType.Stream, ProtocolType.Tcp);

            Platform.Log(LogLevel.Info, "Attempting socket connection to " + ips.GetValue(0).ToString() + " on port " + port.ToString());

            if (tempSocket.Connected)
                s = tempSocket;
                s.SendTimeout = Coordinate.HL7SendTimeout;
                s.ReceiveTimeout = Coordinate.HL7ReceiveTimeout;
                return null;

            return s;
        catch (Exception e)
            Platform.Log(LogLevel.Error, "Error creating socket connection to " + server + " on port " + port.ToString());
            Platform.Log(LogLevel.Error, "The error is: " + e.ToString());
            if (g_NoOutputForThreading == false)
                rtbResponse.AppendText("Error creating socket connection to " + server + " on port " + port.ToString());
            return null;

This is really specific, but if you receive this error after trying to connect to a database using mongo, what worked for me was running mongod.exe before running mongo.exe and then the connection worked fine. Hope this helps someone.

In my case, some domains worked, while some did not. Adding a reference to my organization’s proxy Url in my web.config fixed the issue.

    <defaultProxy useDefaultCredentials="true">
      <proxy proxyaddress="" usesystemdefault="True"/>

I’ve received this error from referencing services located on a WCFHost from my web tier. What worked for me may not apply to everyone, but I’m leaving this answer for those whom it may. The port number for my WCFHost was randomly updated by IIS, I simply had to update the end routes to the svc references in my web config. Problem solved.

In my scenario, I have two applications:

  • App1
  • App2

Assumption: App1 should listen to App2’s activities on Port 5000

Error: Starting App1 and trying to listen, to a nonexistent ghost town, produces the error

Solution: Start App2 first, then try to listen using App1

One more possibility —

Make sure you’re trying to open the same IP address as where you’re listening. My server app was listening to the host machine’s IP address using IPv6, but the client was attempting to connect on the host machine’s IPv4 address.

Go to your WCF project – properties -> Web -> debuggers -> unmark the checkbox

Enable Edit and Continue

In my case this was caused by a faulty deployment where a setting in my web.config was not made.

A collegue explained that the IP address in the error message represents the localhost.

When I corrected the web.config I was then using the correct url to make the server calls and it worked.

I thought I would post this in case it might help someone.

When you call service which has only HTTP (ex: and you call HTTPS (ex:, you get exactly this error – “No connection could be made because the target machine actively refused it”

Using WampServer 64bit on Windows 7 Home Premium 64bit I encountered this exact problem. After hours and hours of experimentation it became apparent that all that was needed was in my.ini to comment out one line. Then it worked fine.

commented out 1 line socket=mysql

If you put your old /data/ files in the appropriate location, WampServer will accept all of them except for the /mysql/ folder which it over writes. So then I simply imported a backup of the /mysql/ user data from my prior development environment and ran FLUSH PRIVILEGES in a phpMyAdmin SQL window. Works great. Something must be wrong because things shouldn’t be this easy.

I came across this error and took some time to resolve it. In my case I had https and net.tcp configured as IIS bindings on same port. Obviously you can’t have two things on the same port. I used netstat -ap tcp command to check whether there is something listening on that port. There was none listening. Removing unnecessary binding (https in my case) solved my issue.

It was a silly issue on my side, I had added a defaultproxy to my web.config in order to intercept traffic in Fiddler, and then forgot to remove it!

There is a service called “SQL Server Browser” that provides SQL Server connection information to clients.

In my case, none of the existing solutions worked because this service was not running. I resumed it and everything went back to working perfectly.

I was facing this issue today. Mine was Asp.Net Core API and it uses Postgresql as the database. We have configured this database as a Docker container. So the first step I did was to check whether I am able to access the database or not. To do that I searched for PgAdmin in the start as I have configured the same. Clicking on the resulted application will redirect you to the There you can try access your database on the left menu. For me I was getting an error as in the below image.

enter image description here

Enter the password and try whether you are able to access it or not. For me it was not working. As it is a Docker container, I decided to restart my Docker desktop, to do that right click on the docker icon in the task bar and click restart.

Once after restarting the Docker, I was able to login and see the Database and also the error was gone when I restart the application in Visual Studio.

Hope it helps.

it might be because of authorisation issues; that was the case for me. If you have for example: [Authorize("WriteAccess")] or [Authorize("ReadAccess")] at the top of your controller functions, try to comment them out.

For me, I wanted to start the mongo in shell (irrelevant of the exact context of the question, but having the same error message before even starting the mongo in shell)

The process ‘MongoDB Service’ wasn’t running in Services

Start cmd as Administrator and type,

net start MongoDB

Just to see MongoDB is up and running just type mongo, in cmd it will give Mongo version details and Mongo Connection URL

I just faced this right now…

enter image description here

Here on my end, I have 2 separated Visual Studio solutions (.sln)… opened each one in their own Visual Studio instance.

Solution 2 calls Solution 1 code. The problem was related to the port assigned to Solution 1. I had to change the port on solution 1 to another one and then Solution 2 started working again. So make sure you check the port assigned to your project.

I had this issue happening often. I found SQL Server Agent service was not running. Once I started the service manually, it got fixed. Double check if the service is running or not:

  1. Run prompt, type services.msc and hit enter
  2. Find the service name – SQL Server Agent(Instance Name)

If SQL Server Agent is not running, double-click the service to open properties window. Then click on Start button. Hope it will help someone.

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