HP Officejet 8500 says "Paper

>Remove back cover(duplex) check any paper object jammed? remove it.. >remove paper tray observe any paper objects visible? remove it>Check paper path sensor located at the path of carriage assembly.. observe for free play of sensor flag...

Here is troubleshooting step for "Paper Jam issue" :
http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01617494&tmp_task=solveCategory&lc=en&dlc=en&cc=us&lang=en&product=3752462
For any jam or feed issue with your product, click this:
http://h10025.www1.hp.com/ewfrf/wc/documentSubCategory?tmp_rule=2777&tmp_task=solveCategory&lc=en&dlc=en&cc=us&lang=en&product=3752462
Hope it helps, Dont forget to rate. Thanks.

This error message is displayed by the printer when paper is jammed in one or more locations. In such a case, users are recommended to remove the jammed paper from the specified location. The entire paper path must be checked for any pieces of paper. To stop the message, open and close the top most cover of the printer. Lastly, verify the flags and the sensors. If the problem persists, the cause of the error message could be a broken sensor or sensor lever.

you need to open the printer and then fix it

i dunno

An error code showing that there is paper jam alert, but no paper is in anywhere in the machine except in the tray.....I have checked all areas, taken the back carriage of the unit, opened the top and opened the machine. removed the paper tray, everything, but there is no paper stuck in the unit

Constant jam indication. This gear is more than likely the cause after exhausting all other avenues. Also nearly impossible to get to let alone replace even if HP offered the part. There is a black cover over the clutch assy that can be removed to reveal the gear. In most cases the gear is either sitting in the bottom of the machine or split down one side. This is the second machine that I have diagnosed with this problem in a very short time. If you have this broken gear, consider it toast. Matt / E-tech Copier and printer repair.

i cant print what happening. Its telling me to load paper but i have paper in slot. This started happening after a paper jam.

Hi! I will be glad to assist you in this issue, here is the link that will fix the issue:

Paper Jam' Message Displays on the All-in-One

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01617494&tmp_task=solveCategory&lc=en&dlc=en&cc=us&product=3752459&lang=en

Carriage Jam' Message Displays on the Control Panel Display

http://h10025.www1.hp.com/ewfrf/wc/document?docname=c01618201&tmp_task=solveCategory&lc=en&dlc=en&cc=us&product=3752459&lang=en