This article is obsolete. Please refer to this article for Google Policy changes from August 2020: Google Play Store Warning: Apps Must Target At Least Android 10 From August 2020
New Android versions will have a higher API level to introduce new features and capabilities for users and developers.
You may receive the following email from Google warning you to publish your APKs at the right API level. In most cases, you'll receive this email if the app has an old published date instead of a recent one.
Hello Google Play Developer, This is a reminder that starting November 1, 2019, updates to apps and games on Google Play will be required to target Android 9 (API level 28) or higher. After this date, the Play Console will prevent you from submitting new APKs with a targetSdkVersion less than 28.
Configuring your app to target a recent API level ensures that users benefit from significant security and performance improvements, while still allowing your app to run on older Android versions (down to the minSdkVersion). Action required Please ensure that your apps are configured to target at least Android 9 (API level 28) by November 1, 2019. For technical advice on how to change your app's target API level to meet these requirements, refer to the migration guide. Affected apps The apps included below have one or more APKs—in production or testing tracks—that aren't currently targeting API level 28 or higher. Apps are listed with the maximum version code and corresponding targetSdkVersion. If you have more than 20 apps that could be affected in your account, please check the Play Console for a full list.
Upon receiving this message, verify the last published date of the affected Android apps in the CMS by following the steps listed in the Checking the Last Published Date of an App article.
To resolve this, republish and upload each app to the Google Play store to meet the new requirements. Follow the steps listed in the Publishing and Uploading Android Apps article.