HP Printer Troubleshooting HP printers are reliable machines that perform excellent printing and ’t negate the fact that the do run into errors from time to time, the cause of a few reasons. Users frequently report common problems like paper jams to 50.4 errors, HP printer offline, ghosting problems, HP Print jobs stuck in a queue, poor print quality, printer not printing color, etc. So, the owners of this printing machine must know about HP printer troubleshooting.