Canon Pixma mx 439 does not work with macOS you need to verify the SSID ( Network Name), your Canon printer and computer both should connect same wifi network, you need reinstall the driver.
Before connecting printer to the network, the computer needs to be connected to the network.
If your canon mx439 driver problem is not fixed, you can reinstall the Canon mx439 printer driver. Another thing you can check ink cartridge in the Canon printer. If it does not work then you need to call customer service.