Having problems getting F# tutorial to work for me in Monodevelop. Composition error: the type 'Object' is required here and is unavailable

Question

I am trying to work an F# tutorial on Pluralsight (see screencaps) where you have to install Xunit and write the tests but it's not working for me. It works fine for someone using Visual Studio as shown in the screencaps below, but I am not using Visual Studio. I'm on a Linux system using Monodevelop and I get this message: Composition error: the type 'Object' is required here and is unavailable. You must add a reference to assembly 'System.Runtime, Version=4.0.0.0, Culture=neutral, PublicKeyToken=b03f5f7f11d50a3a'

I think it must be the Assembly.fs file where I'm supposed to add the reference but I am not sure, nor do I know exactly how to add this reference correctly. Furthermore, I am unsure if the problem may be due to Monodevelop not recognizing a valid Linux path and if so, how to fix that. Any help would be greatly appreciated because I'm completely stuck.

Here is the error I'm getting in Monodevelop:

Answer 1

As already mentioned in the comments, there is not enough information in your answer to give you a proper question. The error generally happens when you add reference to a dll that is itself referencing another dll and you do not have a reference to the other dll. So in general, you can fix this by adding the reference (as mentioned in the error message).

The specific assembly that you're getting an issue on is a core library referenced by portable .NET libraries. Try adding a reference as discussed for example here.

Otherwise, you need to give us more information - what type of project are you creating (what .NET version and profile) and what other libraries are you referencing in your project.