Error consuming web service: An existing connection was forcibly closed

问题

I have a Winforms appplication written in C# that consumes web services from a Windows 2008 IIS Coldfusion server. All the web service calls succeed but one, which fails about 50% of the time with the following error:

System.InvalidOperationException was unhandled by user code Message=There is an error in XML document (1254, 7).

with an inner exception of:

InnerException: System.IO.IOException Message=Unable to read data from the transport connection: An existing connection was forcibly closed by the remote host.

I checked my IIS logs and I get a 503 error (Service Unavailable) and an IIS code of 64 (The specified network is no longer available). Any suggestions would be great.

I run my web service in SOAP UI and I get the following error:

javax.net.ssl.SSLException: Connection has been shutdown: javax.net.ssl.SSLException: java.net.SocketException: Connection reset

This code works fine at one company but this error pops up almost every time for this company I'm currently working with.

回答1:

I recently got a similar message when consuming a WCF-Webservice. In my case it turned out to be a configuration error on the server side. Maybe something is configured differently on the one server where this happens to you? My problem was that the default maximum message size was configured to be too small on the server and this resulted in the same forced connection closing. There is a default maximum message size to avoid DOS attacks...

回答2:

I'm not sure this is applicable to the OP's specific situation, but this may help others who arrive here nowadays. One potential cause for this exception involves mismatched security protocols. If the server you're calling requires TLS 1.2 and you're using an older version of ASP.net (<= Version 4.0) you will be using an older security protocol to make your calls unless you change it. You can force ASP.net to use TLS 1.2 (shown below). This can be done anywhere in the application, but I put it just before the line that calls the web service requiring TLS 1.2:

using System.Net;

...

//Enable TLS 1.2
ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072; 

// Call the Web Service that requires TLS 1.2

回答3:

If you are using a WCF client to connect to the service, enable service trace logging in your client application with the following config:

<system.diagnostics>
    <trace autoflush="true" />
    <sources>
        <source name="System.ServiceModel"
                        switchValue="Error"
                        propagateActivity="true">
            <listeners>
                <add name="sdt"
                        type="System.Diagnostics.XmlWriterTraceListener"
                        initializeData= "ErrorTrace.svclog"
                        />
            </listeners>
        </source>
    </sources>
</system.diagnostics>

Download the windows sdk and you have a nice trace viewer for these log files. It helps you get to the bottom of errors in WCF communication.

回答4:

Using cross platform communication sometimes it happens (once happened to my code) that the exception thrown is not the real description of what is happening inside.

One cause of this exception is that your response time is a little lesser than time required by the webservice method to complete. So try to increase the timeout in your app.config.

If it doesn't work there could be two possible problems in your case.

1. If SSL is used then there is problem with SSL certificate validity.
2. There are some invalid characters used in XML for example your platform doesn't support Unicode characters and there is some un-supported character used in XML.

But I hope just increasing the timeout will fix this.

回答5:

I did get similar error and cause was exception in XML serialization. Mostly if xmlserializer tries to read some property and that get method raises an exception due to some database connection already closed or any resources not available.

Have you tried to log exceptions in error event inside global.asax?

Sometimes if global.asax does not raise error event, then only way to log error through response filter. You can add custom response filter in the web.config, in which you will be able to analyze how much XML was correctly serialized and where it might be failing.

http://msdn.microsoft.com/en-us/library/aa479332.aspx

http://www.raboof.com/projects/elmah/

回答6:

Intermediate "An existing connection was forcibly closed by the remote host" from only one destination sounds like a networking issue to me.

Try getting logs from the server you try to access and from the involved firewalls of both locations. You may run Fiddler or NetMon / WireShark / Ethereal to diagnose further.

回答7:

Connection close happen for any circumstance. Make sure the timeout is abundant on the server and the client, make sure there is no recursion in the data you are returning. Circular reference. Serialization is important in this case because the thing is being serialized when returned.

Do a WCF tracer and check the answer there. Any fault in the server will close the connection. If the server requires username, make sure those are correct. Take care of the SSL error. use WCF client to test the service.

回答8:

This may be a shot in the dark but here is my theory:

The first error is happening on the web service side with a poor exception being thrown, maybe some invalid data is being passing into the service? This could return the error regarding the XML being malformed. I would do several test cases to see what data is being passed into the service and what causes the issue.

The second error I have seen before in a certain circumstance regarding a web service exception being thrown and a try catch wrapped around a using statement for the service. This combination of logic caused an early exit that wasnt cleaned up.

回答9:

try to check the existing protocols in your last company and compare them with your current company,I mean TCP/Ip,...

回答10:

Check the app pool recycling configuration in IIS. I have seen this error, for example, when the "Private Memory Limit" is set to a value (say 100mb) and then the w3wp process exceeds this limit which will cause the app pool to be recycled.

This normally isn't a problem since any existing connections are given time to complete and new connections will be processed by the newly spun-up app pool.

If all the connections are not closed within the shutdown time limit though (normally 90 seconds) then they are killed by IIS and the client may raise the "An existing connection was forcibly closed" error.

来源：https://stackoverflow.com/questions/9117628/error-consuming-web-service-an-existing-connection-was-forcibly-closed