Comment 21 for bug 910272

This looks like a strange special case, as now even the usblp kernel module does not recognize the printer any more. So we need a much more systematic investigation now. Perhaps we have a very bad interference of instabilities of the adapter, the kernel and libusb. Now I need all combinations of systems and CUPS versions. You have two systems (internal and external driver) and two CUPS versions (PPA and proposed). This gives four combinations. Please test all four combinations, running this set of commands, naturally with the printer powered on and connected:

sudo rmmod usblp
lsusb
ls -l /dev/bus/usb/*/*
ls -l /dev/usb/lp*
sudo /usr/lib/cups/backend/usb
ldd /usr/lib/cups/backend/usb | grep usb
lpinfo -v
sudo modprobe usblp
lsmod | grep usb
ls -l /dev/usb/lp*
for d in `ls -1 /dev/usb/lp*`; do sudo usb_printerid $d; done
sudo rmmod usblp

Post all the output (or attach as uncompressed text files).

To do downgrades download all *.deb files of each package from

https://launchpad.net/ubuntu/+source/cups

and

https://launchpad.net/~till-kamppeter/+archive/ppa/+packages

into separate directories (one per version) and do

sudo dpkg -i *.deb

in the appropriate directory to install the desired version.