Symptoms
The Go to Definition sometimes stops working, and I don't know why. The first symptom that this is happening is that the coloring of some class is unaltered (white) when it should be green.Possibly related info
I am using VS 2017 Professional with ReSharper Ultimate.
Ways to fix it in order from least trouble afterwards to most
- Clean solution
 - Close all files
 - Clean solution
 - Restart Visual Studio
 - Recompile all
 
- This did not work for me.
 
- Empty the symbol cache
 - Tools > Options > Debugging > Symbols > EmptySymbolCache
 - Open VS in admin mode
 
- I have not tried this yet.
 
- Delete the .vs folder
 - Close VS
 - Delete the .vs folder from your solution folder
 - Start VS
 - Recompile
 
- I have not tried this yet.
 
- Delete obj and bin folders
 - Close VS
 - Delete obj and bin folders from your project folder
 - Start VS
 - Recompile
 
- I have not tried this yet
 
- Delete the .user file from the project folder (may be hidden)
 - This will reset the customizations you've done to the IDE
 - The user file contains user preferences, such as debugging and deployment settings; used for saving and loading project preferences for a specific user.
 
- I haven't tried this yet.
 
- Run devenv.exe /resetuserdata
 - Devenv.exe may be found in... 
C:\Program Files (x86)\Microsoft Visual Studio 14.0\Common7\IDE - This will reset many of your IDE customizations, including installed plugins.
 - ReSharper has to be repaired afterwards.
 
- This worked for me.
 
Source:
https://stackoverflow.com/questions/33029127/go-to-definition-cannot-navigate-to-the-symbol-under-the-caret