Error "A class is not loaded. (Exception from HRESULT: 0x80131303)"

I am trying to debug arrays using MonoDevelop but I've noticed getting these errors. I am using c# and the program runs fine even with this error, although I'm not able debug it step by step.

int[] a = {1,2,3,4};

I'm not able to see what's in the array "a" in the "Locals." When I try to expand "a" I see the error message, "A class is not loaded. (Exception from HRESULT: 0x80131303)."