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!

Answer 2

Something got messed up on the indexing of the Project when you updated the version.

To fix go to the menu:

File -> Invalidate Caches/Restart

that will reopen and re-index the whole project, the error should be gone.

Answer 3

In my case , I have already defined the value in styles.xml file but it still notice me the problem like this:

But I still got an error like below:

I solve this problem by change the value like below:

Hope this is work for you too.Thank you!

Answer 4

I had this same error so i compared it to gradle file of another project which wasn't showing error. In your build.gradle(Module:app) under dependencies, add the following line:

implementation 'com.android.support:preference-v7:28.0.0'

Answer 5

1)Close the project from the File menu.

2)Open the project again as existing Android Studio project.

This fix my problem.

Answer 6

1. In the app/build.gradle remove the line responsible for the appcompat package (something like implementation 'com.android.support:appcompat-v7:27.1.1')
2. Perform the Gradle sync. It will break and show a lot of errors
3. Bring the original line back
4. Perform the Gradle sync once again

This will magically solve the problem that for no reason appeared in the 3.0.1