INSTALLFAILEDUPDATEINCOMPATIBLE usually means:

  1. The phone is full
  2. The APK has no icon
  3. The emulator is off
  4. The installed app has the same package name but a different signing key
Answer

D) The installed app has the same package name but a different signing key

Uninstall the old version signed with a different key first.

Computer Science MCQ · More Lab: Generating and Installing an APK MCQs · Practise