A tray full of paper does not necessarily satisfy a print job. The job may request a different size, a different type or a different tray. A paper mismatch warning is useful evidence about that disagreement, not an instruction to force the job through.

Write down what each layer says

Read the warning and note the requested paper size and tray. Inspect the physical paper packaging if the size or weight is uncertain. A4 and Letter are different sizes, even when a stack looks similar at a glance.

Next inspect the document's page setup, the application's print settings and the printer properties for this job. HP's mismatch guidance calls for checking the selected size and paper source against what is loaded. On printers with tray registration, also inspect the size and type assigned to that tray at the printer.

A practical note might read: document A4, driver Letter, tray A4 plain. That makes the disagreement obvious. Do not change all three blindly until the warning disappears; choose the settings that describe the intended output and actual media.

Make one compatible job

If the document must print at its original size, load supported matching paper. If resizing is acceptable, choose that deliberately and inspect the new layout. An envelope or label job also needs the correct media type and a tray approved for that material.

Send one short test after correcting the mismatch. Check the physical output, margins and selected tray before submitting the full document. Cancel only obsolete copies of your own failed job so they do not print unexpectedly later.

If the displayed request still disagrees with the saved settings, record the application, driver and exact message. Some faults are model-specific. Keep the evidence rather than disabling paper checks globally, because a future job may depend on those checks to protect special media.

Sources: HP paper mismatch guidance.