Exception The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. (PathTooLongException):

If you are using TDS to sync all of your TDS items in Visual Studio then you might get this error:
Exception The specified path, file name, or both are too long. The fully qualified file name must be less than 260 characters, and the directory name must be less than 248 characters. (PathTooLongException):

The reason why you are getting this error one of the TDS item paths is too long but how to I find which one is the issue as Visual Studio does not list the name of the file in the Output window. You can use Powershell and run the commands below to get the path of this file that's generating this error.

1. Open PowerShell
#change your directory
2. cd <path to solution root>
3.cmd /c dir /s /b |? {$_.length -gt 260} > output.txt

Why is your Razor Page Intellisense in Visual Studio 2017 Community Edition not working?

So your Razor Page Intellisense in Visual Studio is not working properly. You started noticing that your code is being decorated with squiggly underlines. Now What? Well if it's been working properly then I have the easiest solution for you to resolve this issue. All you have to do is check your Local folder. So use the path below to look for these files. These files are located in the Visual Studio folder.

C:\Users\[Your User Profile\AppData\Local\Microsoft\VisualStudio

I noticed that there are three folders starting with 15 so which folder has those files and how do I find out which one to delete?

If you have these three folders there then open each one and look at data stamp on these files inside the ComponentModel Cache Folder. As you see that folder "15.0_fabe3d27" contains these files and the DateTime stamp is the recent one so my Visual Studio is using this folder.

The files will be recreated when you open Visual Studio.