Why so red? IntelliJ seems to think every declaration/method cannot be found/resolved

Question

I just installed and re-installed IntelliJ. Every Java file is coming up RED. I checked the JDK; it is at 1.6.##. The maven clean install build worked just fine

Answer 1

I spent most of a day trying all the solutions here, but nothing seemed to work. The only thing that worked for me was to completely uninstall IntelliJ and install it again. However, for me, when I deleted IntelliJ from the Application folder, the problem returned as soon as I re-installed it. What I finally had to do was to use App Cleaner to completely remove IntelliJ and all the config and settings files. After I did that and then reinstalled IntelliJ, the problem finally went away. See How to uninstall IntelliJ on a Mac