Sometimes when developing web applications, we get an exception when calling web service/another web application with HTTPS on the URL:
The underlying connection was closed: Could not establish trust relationship for the SSL/TLS secure channel.
The best solution is by installing the SSL certificate on the web server, where you can find here. However sometimes your network engineers told you that they have installed it, but it is still throwing an exception.
A workaround to this issue is to bypass the SSL certificate validation. It is not the best solution, but it works, especially when your network people cannot resolve this issue and you have no authority to touch the production server.
Bypass SSL Certificate Validation
To bypass the SSL certificate validation, we will need to add some code like below:
System.Net.ServicePointManager.ServerCertificateValidationCallback = _
Function(se As Object, _
cert As System.Security.Cryptography.X509Certificates.X509Certificate, _
chain As System.Security.Cryptography.X509Certificates.X509Chain, _
sslerror As System.Net.Security.SslPolicyErrors) True
System.Net.ServicePointManager.ServerCertificateValidationCallback = Nothing
The first block will bypass any SSL certificate validation checking, while the last block is to restore the SSL certificate validation checking.