solve error: cannot access Publisher in Android Studio?

Question

I am getting this error while compilation of my code:

Can anyone help me how to solve this error or what might be causing this error?

Edit1: Gradle

Answer 1

Try to update latest versions:

1. RxJava: io.reactivex.rxjava2:rxjava
2. RxAndroid: io.reactivex.rxjava2:rxandroid

Then, AndroidStudio -> File -> invalidate Cashes/Restart.

It helped me.