Android Studio “cannot resolve symbol” but project compiles and works

Question

The project compiles fine. However, Android studio 3.0.1 shows reference to one particular library in red and displays \"cannot resolve symbol\". Even single stepping into

Answer 1

Firsty try to Clean and rebuild project from Build -> Clean project & then Build -> Rebuild project.

If that doesn't work Invalidate Caches/Restart always works for me. Do it from File -> invalidate Caches/Restart

Then click on invalidate and restart

Hopefully this helps.