Visual Studio Editor does not underline errors anymore

Question

My Visual Studio (2008) Editor has stopped to underline Errors (this nifty wavy red lines). I can\'t really tell when, but it can be related to the installation of .Net Fram

Answer 1

I know its an old question, and with various solutions, but I have fixed it in different way. I'm working with Unity3D on my C# code using VS2017, when suddenly VS decides to stop underlining error while im typing. However, if I close the file tab and reopen, it suddenly undelines the error.

For example:

class A { 
public int x; 
s;
}

should obvsiouly give an error for that lonely 's' symbol. But, VS doesn't underline it until I close and reopen this file tab.

Solution: Copied the entire Unity Project folder (which is like a regular VS Solution folder basically) and worked with the new folder, which issue was gone there.