Android Studio “cannot resolve symbol R” but project compiles and runs

Question

Android Studio displays in all java files in red : “cannot resolve symbol R” but the project compiles and runs.

I have tried every solution here: Android Studio "cannot resolve symbol" but project compiles and works, but with no luck.

I tried to :

• invalidate caches and restart android studio

• delete .gradle and .idea folders

• clean and rebuild the project

• install a new version of android studio

• mess up with gradle file then undo changes and sync project

One thing that I want to try, but I don't know how to achieve, is to reopen the project from scratch as I was opening it for the first time, but I don't know how to do this.

I also tried answers from here: Android Studio says "cannot resolve symbol" but project compiles, but again with no luck.

Android studio version = 3.2.1

dependency versions in gradle project file:

classpath 'com.android.tools.build:gradle:3.4.0-alpha01'
classpath 'com.google.gms:google-services:4.0.0'

Answer 1

For some reason that i do not understand ,

this combination of build versions made the issue :

grade version = 4.10.1

classpath 'com.android.tools.build:gradle:3.4.0-alpha01'

when i switched to these build versions :

grade version = 4.6

classpath 'com.android.tools.build:gradle:3.2.1'

The issue was solved !