The server was unable to process the request due to an internal error. For more information about the error, either turn on IncludeExceptionDetailInFaults (either from ServiceBehaviorAttribute or from the configuration behavior) on the server in order to send the exception information back to the client, or turn on tracing as per the Microsoft .NET Framework 3.0 SDK documentation and inspect the server trace logs. + Sharepoint 2010

Go to IIS Manager>SharePoint Web Services\SecurityTokenserviceapplication

Or

C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\14\WebServices\SecurityToken\web.config




        

  
















 <!-- Behavior List: -->

    <behaviors>

      <serviceBehaviors>

        <behavior name="SecurityTokenServiceBehavior" >

          <!-- The serviceMetadata behavior allows one to enable metadata (endpoints, bindings, services) publishing.

               This configuration enables publishing of such data over HTTP GET.

               This does not include metadata about the STS itself such as Claim Types, Keys and other elements to establish a trust.

          -->

          <serviceMetadata httpGetEnabled="true" />

          <!-- Default WCF throttling limits are too low -->

          <serviceThrottling maxConcurrentCalls="65536" maxConcurrentSessions="65536" maxConcurrentInstances="65536" />

          <!—newly added tag to fix this error-->

          <serviceDebug httpHelpPageEnabled="true" includeExceptionDetailInFaults="true" />

        </behavior>

      </serviceBehaviors>

    </behaviors>