Hi. I bought a HP OfficeJet Pro 9019 AIO 2021-07-21 at Elgiganten, Stockholm. It has worked fine during first two months.
When I now want a printout, it is first spitting out papers in an uncontrolled manner; thereafter claiming "Paper tray is open"; thereafter delivering a bunch of papers, including my two-page printout on two different papers in the bunch.
I have emptied the paper tray and put in fresh regular paper, restarted the printer, tried with my HP Smart to find help and restarted the PC. Plus, of course, read everything on HP homepage during two desparate days to get to a human contact!