Android Studio: Installation failed since APK was not signed

Question

I am attempting to run my app in an emulator and have been receiving the following error:

Installation failed since the APK was either not signed, or

Answer 1

This happens often when you install the same app generated on a different computer. Even the unsigned apk has a signature, so your phone is confused why you're trying to install something with the same package name that was generated on a different computer.

Go to your settings -> apps, then find the app in the list, and clear its data and uninstall it.

Then try installing again. That'll fix it.