I got this error when calling a WCF Service over HTTPS. A Similar error can also occurs when you try calling a web service programmatically over SSL (HTTPS) and certificate is either not valid or Certificate is attached to a domain and you are not using the domain name but the machine name or IP address. So, what to do in that case if you don’t care about certificate and would like to accept all certificates. I found that it can be done using one of two ways. 

Main Class – Where you are calling the Web Service, add following Import Statements

Imports System.Security.Cryptography.X509Certificates

Imports System.Net.Security

Imports System.Net

 

Public Class MyWebServiceCall

 

    Public Sub CallServiceUsingFunction()

        'Instanciate the Service here

        'Set all paramaters which you need to pass

        'Before You call the Service

        ServicePointManager.ServerCertificateValidationCallback = AddressOf TrustAllCertificatesCallback

        'Call your service Now.......

    End Sub

 

 

    Public Shared Function TrustAllCertificatesCallback(ByVal sender As Object, ByVal cert As X509Certificate, _

                                                 ByVal chain As X509Chain, ByVal errors As SslPolicyErrors) As Boolean

        Return True

    End Function

    Public Sub CallServiceUsingClass()

        'Instanciate the Service here

        'Set all paramaters which you need to pass

        'Before You call the Service

        Dim CertOverride As New CertificateOverride

        ServicePointManager.ServerCertificateValidationCallback = AddressOf CertOverride.RemoteCertificateValidationCallback

        'Call your service Now.......

    End Sub

End Class

 CertificateOverride Class - An Alternate Option

Public Class CertificateOverride

    Public Function RemoteCertificateValidationCallback(ByVal sender As Object, ByVal certificate As X509Certificate, ByVal chain As X509Chain, _

            ByVal sslPolicyErrors As SslPolicyErrors) As Boolean

        Return True

    End Function

End Class