Publish next version of app but user cannot update via Google Play

Hi everyone,
Currently, my app is version 1.0.0 on Google Play. I build new version 1.1.0 (https://ionicframework.com/docs/v1/guide/publishing.html).

  • Up version in config.xml file
  • Build unsigned apk file
  • Sign unsigned apk file with key file
    But after I published, user cannot see UPDATE button on Google Play. User must uninstall v1.0.0 app and go to Google Play to re-install again.

What is the solution?