VERY frustrated. Installed Yosemite 10.10 via iMac Software Update about 5 days ago. Guess I shouldn't have, because a few days later, my PIXMA MP450 suddenly stopped working. I got a screen message saying printer is offline, even though all cords (connected through USB) were secure & attached. I followed suggestions on Apple website to delete MP450 from printer list then re-add. Deleted, but when tried to re-add, MP450 is nowhere to be found anywhere on computer. The MP450 page on Canon site,
http://www.usa.canon.com/cusa/support/consumer/printers_multifunction/pixma_mp_series/pixma_mp450 says "There is no driver for the OS Version you selected. The driver may be included in your OS or you may not need a driver." Not sure where the above sentence leaves me. Did a Disk Permissions Repair , which showed there were indeed Permissions issues with printer, then restarted. Nothing. I installed at Apple website's suggestion a10.10.1 followup/update which was supposed to fix "bugs" with initial install including printer screws. Didn't work. The printer is certainly not new but worked fine & upgrading to a new OS has never caused something like this to happen.
