Please try the following to see if we can resolve your issue:
1. Open the cover of the printer.
2. Remove all ink tanks from the printer.
3. Lift up the gray locking lever on the side of the ink tank holder.
4. Gently remove the print head from the carriage unit.
5. Place the print head back in and lock the lever down.
6. Place all of the ink tanks back in the printer.
7. Close the cover and turn the printer off.
8. Unplug the power from the printer. Leave the power unplugged for about 5-10 minutes.
Plug the power back in and turn the printer on. If the error persists, please contact our support group using the link below for additional assistance with this issue.
If you've tried the procedures above and the error remains, please reach out to our technical support department through the link below for further assistance.
I am having the same issue with my Pixima MX712. I did call tech support and they recommended I buy a new printer. They had no other repair options other than removing the printhead, putting it back in and turning the printer off and on again. I already tried that per the software recommendations and it didn't work.