I encounter a question with Android device.
The APK is resigned by Appium first, and the resigned APK will be installed on Android device.
But if the App cannot be uninstalled (App is preloaded on Android device), when we install the APK, it will show the message:
Android doesn’t let you install over an existing app unless the certs match.
Appium should be uninstalling the app before attempting to install to avoid this problem.
If appium can’t uninstall then appium also can’t install. You can avoid specifying an APK in this case and just automate the existing version on the device.