Created attachment 14765 [details]
A small executable to reproduce the issue
How to reproduce :
Compile a C# application that uses X509CertificateValidationMode with .NET Framework 4.0. It will work correctly on windows but it will fail with a TypeLoadException on Linux. Tested with mono 4.2.1 and 4.0.
A temporary workaround that I came with to avoid this issue is to use reflection to load the enum type.
System.TypeLoadException: Could not load type 'System.ServiceModel.Security.X509CertificateValidationMode' from assembly 'System.ServiceModel, Version=18.104.22.168, Culture=neutral, PublicKeyToken=b77a5c561934e089'.
- The same code will execute without errors if compiled with .NET Framework 4.5.