How to bypass server certificate error (underlying connection was closed)

Alternative Title 

•  System.Net.WebException: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
• Server Certificate validation error or Invalid server certificate
  

Problem 
There is a server that runs on HTTPS and after making HttpWebRequest to any URL client application throws error massage "The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel."


Error Stack Trace 

The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.Source=System

StackTrace:

       at System.Net.HttpWebRequest.GetResponse()

       at ConsoleApplication1.Healpers.ExecuteGet(String url)

       at ConsoleApplication1.ODataService..ctor(String serviceURL)

       at ConsoleApplication1.Program.Main(String[] args)

       at System.AppDomain._nExecuteAssembly(RuntimeAssembly assembly, String[] args)

       at System.AppDomain.ExecuteAssembly(String assemblyFile, Evidence assemblySecurity, String[] args)

       at Microsoft.VisualStudio.HostingProcess.HostProc.RunUsersAssembly()

       at System.Threading.ThreadHelper.ThreadStart_Context(Object state)

       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean ignoreSyncCtx)

       at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)

       at System.Threading.ThreadHelper.ThreadStart()

  InnerException: System.Security.Authentication.AuthenticationException

       Message=The remote certificate is invalid according to the validation procedure.

       Source=System

       StackTrace:

            at System.Net.Security.SslState.StartSendAuthResetSignal(ProtocolToken message, AsyncProtocolRequest asyncRequest, Exception exception)

Root Cause 
Server is presenting a certificate to the client that is not trusted by either client machine of client application itself.

Solution 
Normally certificate verification bypassing is not suggested but there are several cases in which you know the server is trusted and do not want to take care of certificate validation error,
In such case you can use [ServicePointManager]


ServicePointManager.ServerCertificateValidationCallback = ((sender, certificate, chain, sslPolicyErrors) => true);

Just put one line of code at the start up of your application and it will mimic as certificate is valid. IE also handles the certificate errors in same way.

Multithreaded Application

This solution will not work in Multithreaded environment, we need to modify app.config 

<configuration>

   <system.net>

    <settings>

      <servicePointManager

          checkCertificateName="false"

          checkCertificateRevocationList="false"        

      />

    </settings>

  </system.net>

</configuration>

Refer to

1. http://www.west-wind.com/weblog/posts/2011/Feb/11/HttpWebRequest-and-Ignoring-SSL-Certificate-Errors
2. http://rob.gillenfamily.net/tag/tricks/#fbid=r0NCXNFk0Xr

Further References 

• http://social.msdn.microsoft.com/Forums/en-US/winappswithcsharp/thread/f5821194-4c40-48e7-976c-3dec8864ac59 
• http://dobrzanski.net/2009/04/01/systemnetwebexception-the-underlying-connection-was-closed-could-not-establish-trust-relationship-for-the-ssltls-secure-channel/