“You cannot install this app because another user has already installed an incompatible version on this device”

Question

Trying to install my own app from play store, it says \"You cannot install this app because another user has already installed an incompatible version on this device\"

Answer 1

Since lollipop it looks like the app preferences are associated with the signing key. Since the debug version of the app uses a different signing key, you have to completely uninstall the old debug app, including data.

To do this:

1. Open settings.
2. Choose app.
3. Is should default to the downloaded app list in alphabetical order.
4. You will find the uninstalled applications are not in alphabetical order but actually at the bottom of the list.
5. Click on the application
6. Choose 'Clear Data'

Note - most of this information is the same as another answer by Preethi Rao but my edits have been rejected - also I have zero reputation so cannot actually comment.