NSIS : failed to call a .NET assembly using CLR::call which checks if a web service is running

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CLR

NSIS

Hi,

I have a .Net library which checks if a WCF service is up and running. Below is the function I have used.

 public string VerifySiteExists(string wcfurl)
        {
  HttpWebRequest httpReq = (HttpWebRequest)WebRequest.Create(wcfurl);
  httpReq.AllowAutoRedirect = false;
  HttpWebResponse httpRes = (HttpWebResponse)httpReq.GetResponse();
  if (httpRes.StatusCode != HttpStatusCode.OK)
     result = "OK";
  httpRes.Close();

I have called the same in NISSI using CLR::Call
         CLR::Call /NOUNLOAD "TestService.dll" "TestService.MyClass"  "VerifySiteExists" 1 "https://axx.xx.com/xx/yyy.svc"

But it gives me the error- "Exception has been thrown by target invocation. .

Kindly advice.

Thanks

What I have tried:

I have noticed that it is because of the .Net class HttpWebRequest. If I comment those functions and return a simple "Hello World" string, it works fine. I need to implement another function that needs to connect to SQL db to check if a data exists in a table. Both these cases , I am facing the same issue.