Error 20 on Hewlett Packard printers means that the document you are trying to print is usually too large for the printers on board memory, could be because you have quite alot of jobs in the queue that the printer is storing. Try the following to fix it:
- Press the Resume button on the printer (Usually blinking Orange)
- If the above does not work then turn the printer off for 1 minutes to reset its memory and then on again. You should now be able to print.