Some common HP printer problems include paper jamming, ghosting, toner smearing, and a 50.4 error message. The 50.4 error message means there is a power supply problem.
Other problems include the printer not recognizing a driver for an operating system; this is because HP printers are not compatible with every operating system. As of 2015, some HP printers are not compatible with certain Mac operating systems.
An HP printer may also have trouble printing onto envelopes. This happens if the envelope is too thick or stiff, or when the envelope adhesive seals because it cannot withstand the heat from the printer.