Hi, thank you for contacting JustAnswer.com. My name is Russell. I will do my best to provide the right answer to your question.
I think that the first thing you should try is, turning the machine Off, and then unplugging it from the power for at least 1/2 hour.
If, when plugged in again, and turned On, the message persists, check for whether there are any obviously broken-off or jammed or otherwise visibly defective paper presence sensor switches, anywhere in the paper path.
If none are found, then you may, unfortunately, have to get a service call or repair-servicing on the machine.