App not installed

If you installed debug build in your mobile.. then you need to uninstall it and install signed build.

If it still not installed then your Application related data might be still there in your memory.. ex) if you created any DB from your Application then you need to delete that from memory and try to install your signed build again.

If it still not installed and if you are using lollipop devices.. your Application might be installed in other users account too.. you to switch to other users and go to Settings->Apps->your_application and uninstall it. even check Guest user. your application might be hiding in that too..

I had this issue.. just follow these steps.. then your application can be installed.. :)

I had also same issue when I try to install release build from playstore.

Solution: The reason for the issues is that I did not increment the versionCode in build.gradle of module before uploading the release build to playstore.