i keep getting 'incorrect paper size' errors on the screen even though the tray is loaded correctly with letter paper.

Diagnosis

The "Incorrect Paper Size" error on the HP Color LaserJet Pro MFP M283fdw is typically caused by a mismatch between the physical position of the paper guides and the internal logic of the printer's firmware. This printer uses mechanical sensors (small plastic levers) that trigger when the blue paper guides are snapped into specific detents. If a guide is slightly off-center or hasn't fully "clicked" into the Letter position, the printer registers the tray as "Custom" or "Legal," which conflicts with the Letter size requested by the print driver. Furthermore, this error often stems from a software-hardware mismatch. If the printer's internal settings are set to "Any Size" or "A4" while the physical guides are set to "Letter," the sensor may trigger a conflict during the initial paper-feed sequence. You can confirm this by looking at the printer's control panel under the "Paper Setup" menu; if the tray is listed as anything other than "Letter," the mechanical sensor is failing to communicate the correct size to the board.

How to Fix It

To resolve the sensor mismatch and clear the error, follow these precise steps to reset the tray alignment:

1. Open the main paper tray (Tray 2) and remove all sheets of paper. Do not leave any remnants in the tray.
2. Locate the blue plastic paper width and length guides. Slide the length guide (the one that moves toward the back of the printer) all the way to the rear to reset the mechanism.
3. Slide the length guide forward slowly until it reaches the mark labeled "LTR" or "Letter." You must feel and hear a distinct "click" as the guide snaps into the detent. If it doesn't click, the sensor will not trigger.
4. Adjust the width guides so they are snug against the edges of the paper stack, but not so tight that the paper bows. There should be no gap between the guide and the paper, but the paper should still slide freely.
5. Reinsert the paper stack, ensuring the edges are perfectly squared against the back of the tray.
6. On the printer's touch screen, navigate to Setup > Paper Setup > Tray 2.
7. Change the "Paper Size" setting specifically to Letter and the "Paper Type" to Plain.
8. Press "OK" or "Done" to save these settings and restart any pending print jobs.

If That Didn't Work

• Clear the Print Queue Spooler: Sometimes the error is cached in the Windows print spooler. Go to "Services.msc" on your PC, stop the "Print Spooler" service, navigate to C:\Windows\System32\spool\PRINTERS and delete all files in that folder, then restart the service. This clears any "Legal" or "A4" size requests that are overriding the printer's physical settings.
• Inspect the Sensor Lever: With the tray removed, look into the printer cavity where the tray slides in. Look for a small black plastic actuator lever. If this lever is bent or stuck in the "up" position due to a piece of torn paper or a foreign object, the printer will think a different paper size is loaded regardless of the tray guides. Use a can of compressed air to blow out any debris from this area.
• Update the Driver Defaults: Open "Devices and Printers" on your computer, right-click the M283fdw, and select "Printing Preferences." Ensure the paper size is set to "Letter" here. If it is set to "A4," the printer will reject the Letter paper in the tray to prevent printing off the edge of the page.
• Hard Power Reset: While the printer is ON, pull the power cord directly from the back of the machine. Wait 60 seconds. Plug it back in. This forces the printer to re-poll the mechanical sensors upon boot-up, which often clears stubborn "Incorrect Size" flags.

Heads Up

• Avoid overfilling the tray; exceeding the maximum fill line can put pressure on the guides, pushing them out of their detents and triggering the error again.
• Always use high-quality, moisture-free paper. Damp paper can cause "curling," which tricks the sensors into thinking the paper is a different size or causing a false jam.
• If you frequently switch between Letter and Legal sizes, always update the settings on the printer's touch screen before sending the document from your computer.
• Periodically clean the blue plastic guides with a damp cloth to remove paper dust, which can prevent the guides from snapping firmly into the Letter position.