System.Net.WebException was unhandled

[wfljy2008]

httpResponse = (HttpWebResponse)httpRequest.GetResponse();
this line throw exception.
System.Net.WebException was unhandled
HResult=-2146233079
Message=The remote server returned an error: (500) Internal Server Error.
Source=System
StackTrace:
at System.Net.HttpWebRequest.GetResponse()
at Odata4ConsoleApplication.AuthenticationHelper.PerformAuthentication(Resources context, String aosUrl) in C:\Users\axlocaladmin\Documents\Visual Studio 2015\Projects\Odata4ConsoleApplication\AuthenticationHelper.cs:line 59
at Odata4ConsoleApplication.Program.Main(String[] args) in C:\Users\axlocaladmin\Documents\Visual Studio 2015\Projects\Odata4ConsoleApplication\Program.cs:line 33
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.RunInternal(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state, Boolean preserveSyncCtx)
at System.Threading.ExecutionContext.Run(ExecutionContext executionContext, ContextCallback callback, Object state)
at System.Threading.ThreadHelper.ThreadStart()
InnerException: