Android App Not Install. An existing package by the same name with a conflicting signature is already installed

Question

I had the same error message, but these answers did not help. On a 4.3 nexus 7, I was using a user who was NOT the owner. I had uninstalled the older version but I kept getting the same message.

Solution: I had to login as the owner and go to Settings -> Apps, then swipe to the All tab. Scroll down to the very end of the list where the old versions are listed with a mark 'not installed'. Select it and press the 'settings' button in the top right corner and finally 'uninstall for all users'

The problem is the keys that have been used to sign the APKs, by default if you are running directly from your IDE and opening your Emulator, the APK installed in the Emulator is signed with your debug-key(usually installed in ~/.android/debug.keystore), so if the previous APK was signed with a different key other than the one you are currently using you will always get the signatures conflict, in order to fix it, make sure you are using the very same key to sign both APKs, even if the previous APK was signed with a debug-key from another SDK, the keys will definitely be different.

Also if you don't know exactly what key was used before to sign the apk and yet you want to install the new version of your app, you can just uninstall the previous application and reinstall the new one.

Hope this Helps...

Regards!

 Go to Settings > Apps, find and open the app info. Then, open the overflow menu (3 vertical dots), and choose Uninstall for all users.

Go to Settings > Apps, find and open the app info. Then, open the overflow menu (3 vertical dots), and choose Uninstall for all users.

If you are using the debug apk, the key that is used to sign it is in

C:\Users\<user>\.android\debug.keystore

If you use that same key, there should not be a conflict when installing.

If you don't want to bother with the keystore file, then just remove the package altogether for all users.

Connect your device with Mac/PC and run adb uninstall <package>

Worked for me.

Ref: https://android.stackexchange.com/questions/92025/how-to-completely-uninstall-an-app-on-android-lollipop

There is a difference between signed and unsigned APK files. Most likely you had an unsigned on there previously. You just need to delete the unsigned before you install the signed version. How this can be accomplished varies on the exact version, but in general, go on the emulator to settings-> application, long click your app, and delete/remove/uninstall it.

If above solutions did not work for you then you may have doing something as following ..

1) installing the app from Appstore.
2) updating it with sign APK with same package name updated version.

So basically there are two kinds if APK's.

1) you uploaded on playstore known as original APK.
2) download from playstore known as derived APK.

In this case basically you are downloading derived apk and updating it with original APK.

For let it work fine uploaded new signed released APK in the internal test mode on the Google Play Store and download the derived APK to check the update scenario.