Hi everybody, it took me quite a while to figure this out so I thought I post this here for someone else in need to find this.
I wanted to reinstall my printer Brother HL-3040CN after I upgraded to stretch. That didn't work at first. The installer failed with "Backend /usr/lib/cups/backend/usb does not exist!". ldadmin gave 'Bad device-uri scheme "usb"'. The solution was easy, if I had known what to do: copy /usr/lib/cups/backend-available/usb to /usr/lib/cups/backend/. Doi! Maybe this will help someone in the future. Simon
