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The following code returned an error:(400) bad request:
sub = "";
ServicePointManager.ServerCertificateValidationCallback = new System.Net.Security.RemoteCertificateValidationCallback(AcceptAllCertifications); 
ServicePointManager.Expect100Continue = true;
ServicePointManager.SecurityProtocol = (SecurityProtocolType)(0xc0 | 0x300 | 0xc00 | 0x30); //tls,tls1.1,tls1.2,ssl3
System.Net.WebClient wc = new System.Net.WebClient();
byte[] raw = wc.DownloadData(sub);
string webData = System.Text.Encoding.UTF8.GetString(raw);

AcceptAllCertifications is defined as:
public bool AcceptAllCertifications(object sender, System.Security.Cryptography.X509Certificates.X509Certificate certification, System.Security.Cryptography.X509Certificates.X509Chain chain, System.Net.Security.SslPolicyErrors sslPolicyErrors)
    return true;

I am using VS2010 c#, windows 7.

What I have tried:

The code incorporates every suggestion I have found on the internet. Any other ideas would be greatly appreciated.
Updated 10-Aug-19 7:28am

Because you are using an older Windows version and probably an older .NET version, this could be a TLS issue.
More information here: Transport Layer Security (TLS) best practices with the .NET Framework | Microsoft Docs[^]
The simplest way to solve this is to use .NET Framework 4.7 or later.
Also see: your-net-code-could-stop-working-in-june[^]
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Thank you. I had sort of decided the same thing but cannot install a higher version of NET on Windows 7. I am in the process of upgrading to Windows 10 and VS 2012 which hopefully will solve my problem.
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Member 11170300 10-Aug-19 14:58pm    
Unfortunately, not resolved.

I am now running Visual Studio 2012 on Windows10 and targetting .NET4.5 but getting the same error message with unchanged code
Member 11170300 10-Aug-19 17:23pm    
I've now upgrade to .NET 4.8. Still failing.
Richard Deeming 13-Aug-19 13:15pm    
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