Cannot resolve symbol Theme, ThemeOverlay

Question

I updated my android studio to latest version - 3.0.1. Since then it complains \'Cannot resolve symbol\' for Theme and ThemeOverlay in the following lines of code. App runs

Answer 1

Found Easiest Way

• Close project (File> Close Project)
• Import / Re-Open project again (NOT from Recent)

The error should be gone.

If(that_did_not_work)

• Open build.gradle, remove appcompact-v7 dependency and sync.
• Again add that dependency and sync.

Error Gone!