Android Lollipop (5.0) comes with a full set of new features.
A set of new features in Android often comes with a set of new bugs.
One of the toughest so far has been
Unknown error code during application install: "-505"
while trying to reinstall an application after having uninstalled it.
That apparently has something to do with duplicate permissions and still apparently is fixed 5.0.1 (meaning that it shouldn't appear if you start installing apps from this version on).
If you are one the lucky guys, as me, to have been on board of Lollipop 5.0 you can try to prevent this bug by not simply uninstalling the Applications as you're used to do but with the "Uninstall for all users" feature that pops down from the upper right menu button (from System > Apps > Application).
If you're late and this post didn't save your day yet, fear no more!
You can still try to manually uninstalling the Dying Hard app with
adb shell pm uninstall com.domain.app
or if you hate Android SDK or your Terminal or even your USB cable then you can try and switch accounts from the upper right icon in your Notification Bar and manually uninstall the Application from every logged user.
Then feel free to reinstall your preferred app.