问题
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 Framework 3.5 SP 1 or the MVC Beta (which I guess is unlikely). Furthermore have I installed and uninstalled both CodeRush and Resharper for evaluation purposes (decided not to keep either one of them).
Does anyone know the problem and how to restore this functionality again?
回答1:
Have you checked Tools→Options...→Text Editor→C#→Advanced→Underline errors in the editor?
I usually like to reset my settings after messing around with plugins, as they tend to mess with settings: Tools→Import and Export Settings...→Reset all settings.
回答2:
About possible causes.
For VS 2012 and 2013 if you have more than one instance of Visual Studio on different machines binded to one "live" account and have installed ReSharper on one of them, it disables the native IntelliSense and error underlines (to replace by it's own rules) that will be synchronised through your account to another machine without ReSharper.
回答3:
This is generally called Disable Squiggly or Wavy lines in Visual Studio.
How you will do in Visual studio 2013?
TOOLS -> Options... -> Text Editor -> C/C++ -> Advanced -> Disable Squiggles: True/False (Under IntelliSense) -> Press OK
回答4:
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.
回答5:
I had the same issue with 2017. There was a 'disable intelisense' option, make sure that is set to false.
回答6:
For visual studio 2017 act according to HeeJae's comments in:
https://developercommunity.visualstudio.com/content/problem/113112/design-time-error-checking-isnt-working.html
i.e:
Hi. you are probably hitting a known issue. can you try this?
1.Update to latest release If that doesn’t solve it
2.Go to Tools\Options\Projects and Solutions\General and uncheck “Allow parallel project initialization”.
3.Close VS.
4.Delete the “.vs” directory beside their solution file.
5.Reopen VS.
..
thank you
You can re-enable the "Allow parallel project initialization" option after the issue was solved.
I tried to upgrade VS, reset VS settings, clear VS cache and everything people do conventionally but none of them solved this issue! At the end the mentioned solution worked for me magically.
Good luck
来源：https://stackoverflow.com/questions/267843/visual-studio-editor-does-not-underline-errors-anymore