The request was aborted: Could not create SSL/TLS secure channel.

We recently moved to a server 2016 machine and we had the following error:

“The request was aborted: Could not create SSL/TLS secure channel.”

After some playing around and everything I found out that if I put in the following line of code before all cert calls it works fine:

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

When we were on Server 2008 this wasn’t an issue. I’ve seen this as an error on other libraries as well and they ended up forcing Tls in the library. What was odd was I had no problem locally when testing, only when deployed to the server.

[chrisdunelm]

I’m not exactly clear what’s going on here. .NET4.6 changes the default set of enabled SSL/TLS protocols from .NET4.5 Windows Server 2016 appears to now explicitly not support SSL, only support TLS.

So this might be a combination of code built for .NET4.5, which is trying to use SSL by default (rather than TLS) on Windows 2016 (which doesn’t support SSL), although I’m not clear if this is really the case.

I agree that the client library code shouldn’t force ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;, although we could possibly OR in Tls12 support. I.e. have ServicePointManager.SecurityProtocol |= SecurityProtocolType.Tls12; somewhere in the library code; although it is possible this may break some code.

Unfortunately I can’t see a way to just enable TLS support for the HttpClient that we use. It appears to only be a global setting.

[Eckee]

@jskeet I’m so sorry, I found the solution in another thread, I had to manually update to 1.24, that was the case.