Web Client Exception: The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel

Question

I have a simple app that uses the C# Web Client class to download a websites HTML. This is a stripped down sample of the code I\'m using:

WebClient wc = new Web         


        

Answer 1

Try this:
What you would want to do is, to install the certificate into your local machine.

The procedure if it was not in code would be to do the following:

1. Open Internet Explorer in Administrator mode (not Chrome).
2. Go to the site
3. Select proceed
4. Click the titelbar / url bar on the certificate, to view the certificate.
5. Click install certificate.

So you can try to have a look at these other questions and see if they help you:

• How can I install a certificate into the local machine store programmatically using c#?
• Install certificates in to the Windows Local user certificate store in C#

Try to install the certificate and see if you go to the url again, if it asks to proceed.

****EDIT**:
I read the site certificate, it is because there is a mismatch between the certificate and the site's url.

A simple change would be this:

htmlCode = wc.DownloadString("https://oig.hhs.gov/exclusions/exclusions_list.asp");

Just remove the www.