Review summary Errors
Resolve these errors before starting the rollout of this release. You can’t rollout this release because it doesn’t allow any existing users to upgrade to the newly added APKs.
The issue is the android:versionCode in the AndroidManifest.xml is lower than the previous release.
How to fixed the issue
Change the android-versionCode to a higher value.
Full reply from Google
Thanks for contacting Google Play Developer Support.
You’re seeing that error message because your new APK has a lower version code than the previous APK. Newer APKs must always have a higher version code than the previous version, or the Play Store won’t know that the new APK is an update.
Google Play Developer Support