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

Invalidate cache/restart didn't work for me.
Simple and working solution:
1: Remove all dependencies from App level Gradle and Sync.
2: Re-add all these dependencies and Sync.

It will work fine.