#StackBounty: #c# #ssl #wsdl SoapHttpClientProtocol and TLS 1.2 – The client and server cannot communicate, because they do not possess…

Bounty: 50

There are numerous posts on SO about this and I have scoured them, but still don’t have a solution. I am hoping that someone can point me in the right direction.

We have a requirement now to use TLS 1.2 to connect to a remote provider. So I have installed Windows Server 2016 and configured it as needed:

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I know the remote server is running TLS 1.2 and that it supports the highlighted cipher.

We connect to the remote end point using C# proxy class generated by the WSDL provided by the provider – before they converted their end to TLS (System.Web.Services.Protocols.SoapHttpClientProtocol).

When I connect using the proxy I get an exception with the inner exception being “The client and server cannot communicate, because they do not possess a common algorithm”.

I cannot see anywhere that ServicePointManager.SecurityProtocol so I am assuming .NET is picking up TLS 1.2 as it is the only enabled protocol? No idea how it is doing the cipher.

Can someone tell me how I go about attempting to fix this? If possible I don’t want to regenerate the WSDL proxy class.

Get this bounty!!!

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