How SSL TLS 1.2 upgrade create SocketExceptions in .Net Framework

In my team we have had some dependencies (APIs, image providere ect.) which have upgraded to TLS 1.2 (as they should), but our older .Net Framework solutions dosent age well with this.

These errors occured in a very strange way as a SocketException, somewhing we else where have chained with broken networks, misconfigured firewalls and socket exhaustions.

But .Net Framework (older han XX) cant communicate with connection which uses SSL TLS 1.2 and newer and throws the following exception:

INSERT EXCEPTION

The fix for us is “just” to upgrade to .Net Framework 4.7.2 trough a simple change in the targetFramework proptery in httpRuntime (and maybe other places) in the web.config.

https://docs.microsoft.com/en-us/dotnet/framework/network-programming/tls