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LitJSON causes System.MissingMethodException : No parameterless constructor defined for this object.

November 3, 2019 1 min read Luke Chadwick

This post is 7 years old. It was originally published on vertis.io; links and advice may have aged.

Filing another report under hard to google errors, which seems to be my primary reason for posting on this blog these days.

Was working with LitJSON in C# to deserialize an API response. When I started getting System.MissingMethodException : No parameterless constructor defined for this object..

This error message is too generic to Google, and there is nothing in the results related to LitJSON really. Turned out I had a really simple problem though.

My class was something like this


public class Foo {
  public string bar
}

When in reality to JSON was:


{
  "bar": {}
}

Calling:

var jsonObject = JsonMapper.ToObject<Foo>(res.body);

Works much better when you're not trying to shove a Map into a string.