How can I identify the root cause of a 422 error when uploading an APK?

Start by checking the Google Play Console's detailed error messages. These often provide clues about the specific issue. Also, use Android Studio's 'Build Analyzer' to check for potential problems in your APK's structure and dependencies. Finally, try uploading a simpler APK (e.g., a 'Hello World' app) to see if the issue is with your project or the upload process itself.