Thanks for your feedback.

Got it, false alarm.

The error is:
---------------
Exception has been thrown by the target of an invocation
at System.RuntimeMethodHandle.InvokeMethod(Object target, Object[] arguments, Signature sig, Boolean constructor)
at System.Reflection.RuntimeMethodInfo.UnsafeInvokeInternal(Object obj, Object[] parameters, Object[] arguments)
at System.Reflection.RuntimeMethodInfo.Invoke(Object obj, BindingFlags invokeAttr, Binder binder, Object[] parameters, CultureInfo culture)
at System.RuntimeType.InvokeMember(String name, BindingFlags bindingFlags, Binder binder, Object target, Object[] providedArgs, ParameterModifier[] modifiers, CultureInfo culture, String[] namedParams)
at Microsoft.SqlServer.Dts.Tasks.ScriptTask.VSTATaskScriptingEngine.ExecuteScript()
--------------

The SSIS catch here is - when the dll version is upgraded, the script task is still compiled with the old one and gave me that strange error. This get fixed with just open the script and saving it. And also the version that is referenced in the script project and the one in GAC must be the same.

Keep up the good work!

It have me very strange error - "Exception has been thrown by the target of an invocation" that went away after recompiling it from the source with target 4.5 but may be some side effect hmm...

Can you explain why an assembly compiled against .NET 2.0 cannot work with SSIS 2017?

Please recompile and sign the .NET assembly with .NET 4.5 support for SSIS 2017. It works fine.