Comment 38 for bug 995111

Stéphane, the usblp module can still be the culprit. For example reattaching it after a job can get some printers into an undefined state. Especially if you never observe the problem with the module blacklisted and sometimes observe the problem with the module not blacklisted, the module can have caused your problem. Then you should try a less invasive solution than blacklisting the module, simply preventing the CUPS backend to re-attach the module after a job, via

lpadmin -p Canon_iP4200 -o usb-no-reattach-default=true

To remove the setting, run

lpadmin -p Canon_iP4200 -R usb-no-reattach

You should do very many tests now (aro, as your problem occurs only sometimes. Also always run

cancel -a
sudo rmmod usblp

and then turn off and turn on your printer after each change of the testing mode and after each occurrence of the problem). Try the following three modes (do never use the forced uni-directional mode):

1. Kernel module not blacklisted, no re-attaching module after job

2. Kernel module not blacklisted, re-attaching module after job

3. Kernel module blacklisted