If the paper is not sitting in the tray properly, or else the paper sensor may need to be cleaned – they sometimes accumulate paper fibers, and need to be blown out with canned air.
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Check out the printer properties. Are you trying to print from the correct paper tray? Do you have the correct paper size for the form/document you are trying to print?
If so, then remove tray(s) and try cleaning with a can of compressed air as mentioned above.