Mojave does not work with Canon printer

I think the choices are downgrade, buy a new printer, or wait for Canon to issue new drivers, which it doesn't look too good for...

Mac OS X Compatibility

It is always important to check with the manufacturers of items to see if they have available drivers for the new operating system before upgrading. The last operating system supported is High Sierra, did you install these drivers when you were on High Sierra, if not it may help to do so, it won't do any harm.

https://www.canon.co.uk/support/consumer_products/products/fax__multifunctionals /inkjet/pixma_mx_series/pixma_mx434.aspx…

Have you tried resetting the printing system, If you can't print from your Mac or iOS device - Apple Support

scroll down the page to resetting the print system.

I have a 10 year old HP printer/ scanner which the drivers have not been updated for about 5 years but it still functions in Mojave. It needed me to remove it from the printer list in System Preferences> Printers & Scanners, restart the Mac and add it back in to that list, and it got full functionality. Try that and see if you can now use your Canon.

Canon have decided NOT to update the drivers for a number of their printers, and they don't appear to be bothered by the feedback. I intend to stop buying their products as a consequence, my printer is only two years old and no longer functions at all.

Mine too. This is ridiculous.