CODEWITHSUNDEEP
c#reflectionasp.net-corednxcoreclr
henningst
henningst

Reputation: 1684

Activator.CreateInstance throws 'System.MissingMethodException' when using CoreCLR

I'm trying to create an instance of a class in my CoreCLR app, but when I call Activator.CreateInstance, I get a System.MissingMethodException saying that it can't find a constructor on the class it's trying to create. The class indeed has a constructor. What am I doing wrong?

The project is only targeting dnxcore50.

This is the code:

using System;

namespace MyNamespace
{
    public class Program
    {
        public void Main(string[] args)
        {
            Activator.CreateInstance(typeof (MyClass), true);
        }
    }

    public class MyClass
    {
        public MyClass() { }
    }
}

And this is the exception:

System.MissingMethodException was unhandled by user code
  HResult=-2146233069
  Message=Constructor on type 'MyNamespace.MyClass' not found.
  Source=mscorlib
  StackTrace:
       at System.RuntimeType.CreateInstanceImpl(BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes, StackCrawlMark& stackMark)
       at System.Activator.CreateInstance(Type type, BindingFlags bindingAttr, Binder binder, Object[] args, CultureInfo culture, Object[] activationAttributes)
       at System.Activator.CreateInstance(Type type, Object[] args)
       at MyNamespace.Program.Main(String[] args) in C:\projects\coreclrplayground\InvokeMember\src\InvokeMember\Program.cs:line 9
  InnerException:

Upvotes: 2

Views: 2270

Answers (1)

Kévin Chalet
Kévin Chalet

Reputation: 42030

On CoreCLR, Activator doesn't have an overload accepting a boolean parameter indicating whether non-public constructors can be used to instantiate the type.

Your snippet builds correctly because the compiler chooses the CreateInstance(Type type, params object[] args) overload, which treats your boolean like a constructor parameter: since your constructor is parameterless, an exception is thrown.

Upvotes: 3

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