TLS 1.2 error Could not create SSL/TLS secure channel

Question

I am trying to integrate Salesforce with .Net API using .Net 4.5.2. My API running on the server which has Windows 2008 R2 and I checked in internet properties TLS 1.2 is checked also I have checked from this link and I get Probably Ok back. Which means I do have TLS 1.2 enable in my server.

In .Net API I have added below code

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12;

When I try to connect I get following error

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

For testing I started using ASP.net web to integrate with this API and I do get same error but if I change above code to allow all protocols

ServicePointManager.SecurityProtocol = SecurityProtocolType.Ssl3
  | SecurityProtocolType.Tls
  | SecurityProtocolType.Tls11
  | SecurityProtocolType.Tls12;

I don't get any error and I can connect to my API. Which explains my server not able to establish connection on TLS 1.2. What have I missed here?

VMAtm VMAtm · Accepted Answer · 2017-10-27T21:51:43

It looks like the problem is in the client, not the server. You can see that the Microsoft blogs suggest exactly the code you've already use:

ServicePointManager.SecurityProtocol = SecurityProtocolType.Tls12

For .Net 4.0 with 4.5 installed on the machine you can use this:

ServicePointManager.SecurityProtocol = (SecurityProtocolType)3072;

For earlier version of .Net there are some patches to use the TLS 1.2.

TLS 1.2 error Could not create SSL/TLS secure channel

2 Answers