i also get same situation. How to solve it

Target API level requirements from August 2019
Warning:

Your app currently targets API level 27 and must target at least API level 28 to ensure it is built on the latest APIs optimized for security and performance.

From August 2019, new apps must target at least Android 9.0 (API level 28).
From November 2019, app updates must target Android 9.0 (API level 28).

Tip:

Change your app's target API level. Learn how.