As the backends do not filter data but simply pass the data through it is not clear whether the "usb" CUPS backend really causes the problem. Especially in this case the CUPS backend still lets go data to the printer and the printer prints something.
So before modifying the backend behavior I would like to know what kind of data you feed to the printer and what does CUPS exactly do. Did you create a CUPS queue with a driver/PPD file? Which driver or PPD file (please attach your print queue's PPD file from /etc/cups/ppd/)? Or did you create a raw (unfiltered) queue? How do you send jobs to CUPS? Do you simply send them or do you use the "-o raw" option (unfiltered by-job)? Are you sending jobs as plain text or as PDF, PostScript, ...? If you add the quirk rule to blacklist your printer the "usb" CUPS backend would ignore the printer preventing the backend to discover the printer. How are you using the printer then? Another CUPS backend? Which one? No use of CUPS at all (like "cat file > /dev/usb/lp0")? Are you using a driver/filter then? Please also follow the instructions of the sections "CUPS error_log", "USB printer", "Capturing print job data", and "Getting the data which would go to the printer" for the case when you are using the "usb" CUPS backend without changes in the quirk rules and also when using CUPS with the change. also run sudo lsusb -vvv > lsusb-out.txt and attach the resulting file. Please do not compress any of the files you get and do not package them together. Attach them to this bug report one by one. ** Changed in: cups (Ubuntu) Status: New => Incomplete -- You received this bug notification because you are a member of Desktop Packages, which is subscribed to cups in Ubuntu. https://bugs.launchpad.net/bugs/1695884 Title: usb probing malforms Epson TM-T70 label printer output Status in cups package in Ubuntu: Incomplete Bug description: CUPS USB probing malforms Epson TM-T70 (vendorid: 0x04b8 productid: 0x0202) which is used outside CUPS (via usblp driver). No matter whether the printer is set up as a CUPS raw printer or it's not used via CUPS (but rather via a device node under usblp control) the formatting is broken on the printed out labels: the orientation is different from what had been set, the fonts differ. After blacklisting the printer in the quirks file all the problems were gone. My assumption is that this printer should be blacklisted by default. To manage notifications about this bug go to: https://bugs.launchpad.net/ubuntu/+source/cups/+bug/1695884/+subscriptions -- Mailing list: https://launchpad.net/~desktop-packages Post to : desktop-packages@lists.launchpad.net Unsubscribe : https://launchpad.net/~desktop-packages More help : https://help.launchpad.net/ListHelp