In order to easily manage a few different users for development (so that I don't have to modify my own user's permissions); I created a new user with an email such has foo+bar@email.tld. I received the user signup notification, but could not set the password. When I attempted to reset the user's password, I again received the password email but was unable to reset the user's password.
The error displayed is simply the "There was an error resetting your password." message.