The printer isn't picking up paper
Take the stack out, fan it, square it off, and load it again with the guides pushed snug against the edges. Don't fill past the line inside the tray. Then check you're loading the tray the printer is actually asking for, because these machines have a rear tray and a front cassette and they complain about them separately. Curled or damp paper causes this too, so try a few sheets from the middle of a fresh ream.