Taking the course on udemy and Visual Studio started throwing System.blah not found errors
VS was working fine as an editor until it randomly decided to throw "Predefined type 'System.Object' is not defined or imported."( same with these libraries System.void or System.single).
Can't find anything helpful online regarding this. Had anyone had this issue?
Also, out of curiosity, is there an IDE out there that works well with Unity but is a little more user friendly that VS. (for example, I like Eclipse, Netbeans, and Pycharm).
With regards to you exception, I suspect that your csproj file has become corrupted and is missing some references. It could also be that you done something strange lik echanges to project to be a .NET Core one or something along those lines.
A starting point to debug would be to create a new, empty Unity project and have a look at the csproj and compare the two.