MSB4025: The project file could not be loaded. Data at the root level is invalid. Line 1, position 1

using System;

namespace FavoriteNumber
{
    class Program
    {
        static void Main(string[] args)
        {
            // Ask user for favorite number
            int favNumber;
            Console.Write("Enter your favorite number: ");

            // Turn the answer into an int
            favNumber = Convert.ToInt32(Console.ReadLine());
            Console.WriteLine($"Your favorite number is {favNumber}!");
        }
    }
}