adb uninstall failed

Question

I am writing some sample apps.
After I debug these apps, I don\'t see an uninstall button in my device\'s application management.
When I do adb uninstall, it always

Answer 1

In my case I often get this issue when I first complise a app in debug mode and later try to install the google signed app.

That is because both apps have the same package name but diffent signatures. Since I upgraded to Android lollypop I sometimes even get this error if I uninstall the app via the settings\Apps. If you have this problem check if the app is installed in a other User profile and uninstall it in all user accounts.