Get error when attempting upgrade from .16 to .17

I’ve included a screen shot of the error. Its telling me that i have modified the login.html file but i have not. i haven’t modified any files.

I checked the status page, re-ran setup, and rebooted the box.

All checks are green except for the one about the upgrade to v0.17.

What can i do from here to upgrade succesfully and avoid this error in the future?