Large WCF web service request failing with (400) HTTP Bad Request

I've encountered this apparently common problem and have been unable to resolve it.

If I call my WCF web service with a relatively small number of items in an array parameter (I've tested up to 50), everything is fine.

However if I call the web service with 500 items, I get the Bad Request error.

Interestingly, I've run Wireshark on the server and it appears that the request isn't even hitting the server - the 400 error is being generated on the client side.

The exception is:

System.ServiceModel.ProtocolException: The remote server returned an unexpected response: (400) Bad Request. ---> System.Net.WebException: The remote server returned an error: (400) Bad Request.

The system.serviceModel section of my client config file is:

 <system.serviceModel>
    <bindings>
        <wsHttpBinding>
            <binding name="WSHttpBinding_IMyService" closeTimeout="00:01:00"
                openTimeout="00:01:00" receiveTimeout="00:10:00" sendTimeout="00:01:00"
                bypassProxyOnLocal="false" transactionFlow="false" hostNameComparisonMode="StrongWildcard"
                maxBufferPoolSize="524288" maxReceivedMessageSize="2147483647"
                messageEncoding="Text" textEncoding="utf-8" useDefaultWebProxy="true"
                allowCookies="false">
                <readerQuotas maxDepth="32" maxStringContentLength="8192" maxArrayLength="2147483647"
                    maxBytesPerRead="4096" maxNameTableCharCount="16384" />
                <reliableSession ordered="true" inactivityTimeout="00:10:00"
                    enabled="false" />
                <security mode="None">
                    <transport clientCredentialType="Windows" proxyCredentialType="None"
                        realm="" />
                    <message clientCredentialType="Windows" negotiateServiceCredential="true"
                        establishSecurityContext="true" />
                </security>
            </binding>
        </wsHttpBinding>
    </bindings>
    <client>
        <endpoint address="http://serviceserver/MyService.svc"
            binding="wsHttpBinding" bindingConfiguration="WSHttpBinding_IMyService"
            contract="SmsSendingService.IMyService" name="WSHttpBinding_IMyService" />
    </client>
</system.serviceModel>

On the server side, my web.config file has the following system.serviceModel section:

<system.serviceModel>
    <services>
        <service name="MyService.MyService" behaviorConfiguration="MyService.MyServiceBehaviour" >
            <endpoint address="" binding="wsHttpBinding" bindingConfiguration="MyService.MyServiceBinding" contract="MyService.IMyService">
            </endpoint>
            <endpoint address="mex" binding="mexHttpBinding" contract="IMetadataExchange"/>
        </service>
    </services>
    <bindings>
      <wsHttpBinding>
        <binding name="MyService.MyServiceBinding">
          <security mode="None"></security>
        </binding>
      </wsHttpBinding>
    </bindings>
    <behaviors>
        <serviceBehaviors>
            <behavior name="MyService.MyServiceBehaviour">
                <!-- To avoid disclosing metadata information, set the value below to false and remove the metadata endpoint above before deployment -->
                <serviceMetadata httpGetEnabled="true"/>
                <!-- To receive exception details in faults for debugging purposes, set the value below to true.  Set to false before deployment to avoid disclosing exception information -->
                <serviceDebug includeExceptionDetailInFaults="true"/>
            </behavior>
        </serviceBehaviors>
    </behaviors>
</system.serviceModel>

I've looked at a fairly large number of answers to this question with no success.

Can anyone help me with this?

Try setting maxReceivedMessageSize on the server too, e.g. to 4MB:

<binding name="MyService.MyServiceBinding" maxReceivedMessageSize="4194304">

The main reason the default (65535 I believe) is so low is to reduce the risk of Denial of Service (DoS) attacks. You need to set it bigger than the maximum request size on the server, and the maximum response size on the client. If you're in an Intranet environment, the risk of DoS attacks is probably low, so it's probably safe to use a value much higher than you expect to need.

By the way a couple of tips for troubleshooting problems connecting to WCF services:

• Enable tracing on the server as described in this MSDN article.

• Use an HTTP debugging tool such as Fiddler on the client to inspect the HTTP traffic.

For what it is worth, an additional consideration when using .NET 4.0 is that if a valid endpoint is not found in your configuration, a default endpoint will be automatically created and used.

The default endpoint will use all default values so if you think you have a valid service configuration with a large value for maxReceivedMessageSize etc., but there is something wrong with the configuration, you would still get the 400 Bad Request since a default endpoint would be created and used.

This is done silently so it is hard to detect. You will see messages to this effect (e.g. 'No Endpoint found for Service, creating Default Endpoint' or similar) if you turn on tracing on the server but there is no other indication (to my knowledge).

I was also getting this issue also however none of the above worked for me as I was using a custom binding (for BinaryXML) after an long time digging I found the answer here: Sending large XML from Silverlight to WCF

As am using a customBinding, the maxReceivedMessageSize has to be set on the httpTransport element under the binding element in the web.config:

<httpsTransport maxReceivedMessageSize="4194304" /> 

In the server in .NET 4.0 in web.config you also need to change in the default binding. Set the follwowing 3 parms:

<basicHttpBinding>  
    <!-- http://www.intertech.com/Blog/post/NET-40-WCF-Default-Bindings.aspx  
         Enable transfer of large strings with maxBufferSize, maxReceivedMessageSize and maxStringContentLength
    -->  
       <binding **maxBufferSize="2147483647" maxReceivedMessageSize="2147483647"**>  
          <readerQuotas **maxStringContentLength="2147483647"**/>            
       </binding>
</basicHttpBinding>