Lexmark Error 34 — What It Means & How to Fix It
By Ryan Green · Updated August 2026 · Independent guide · PrinterCare USA LLC (not affiliated with any printer manufacturer)
Lexmark error 34 is frustrating because your printer seems to be rejecting perfectly good paper. This error specifically means the printer's internal sensors detected that the paper in the tray is shorter than the paper size you told the driver to use, which creates a mismatch that halts your print job.
The good news is that error 34 is usually fixable without a service call. Most of the time it is caused by incorrect paper size selection, paper that has absorbed humidity and curled slightly, or sensors that need a simple cleaning. This guide walks you through the most effective fixes in order from simplest to most involved.
How to fix it — step by step
- Power cycle your printer completely. Turn off your Lexmark printer using the power button and unplug it from the electrical outlet. Wait for exactly 30 seconds to allow the internal memory to clear. Plug the printer back in and power it on. This resets the paper sensor logic and clears any temporary error states that might be causing a false positive.
- Remove and inspect all paper from every tray. Open all paper trays on your printer and remove every sheet of paper. Check for any curled, bent, or damp paper that might be causing thickness inconsistency. Even a small curl from humidity can trigger the short paper sensor. Look for any visible debris or crumpled corners that would prevent smooth feeding.
- Verify your driver settings match your actual paper. On Windows 11, go to Settings > Devices > Printers and Scanners, find your Lexmark printer, click it, then select Printing Preferences. On macOS, go to System Settings > Printers and Scanners, select your printer, then click Options and Supplies. Make absolutely certain the paper size setting matches the paper you are about to load. For example, if you are loading letter size, the driver must be set to Letter, not Legal or Tabloid.
- Load paper correctly into the main tray. Take a fresh ream of paper in the correct size and load it into the main paper tray. Fan the paper before loading to separate any stuck sheets and allow air to circulate. Ensure the paper sits flat and the tray guides are adjusted snugly against the edges without bending the paper. Do not overfill the tray beyond the maximum fill line.
- Clean the paper sensor with compressed air. Locate the paper sensor inside your printer by consulting your specific model's manual, which is usually found on Lexmark's support website. Use a can of compressed air held upright to gently blow away dust and debris from the sensor lens. Do not touch the sensor with your fingers or any physical object, as this can damage it. Allow 10 seconds for any loose particles to settle before closing the printer.
- Check the paper tray itself for damage. Remove the paper tray completely and inspect it for cracks, warping, or broken guide rails. If the tray is warped, it will not hold paper flat, and the sensors will misread the height. Also check that the tray rollers spin freely without grinding or resistance. A damaged tray may need replacement, which typically costs $35 to $60 depending on your model.
- Run a test print from your computer. Send a simple text document to your Lexmark printer and watch it carefully during the feed cycle. If error 34 appears again, note whether it happens immediately or after a few sheets. If it happens after several sheets, your paper may have too much moisture. Try a different brand of paper or store your current paper in a dry location for 24 hours before trying again.
- Request remote diagnostic support if error persists. If error 34 continues after all the above steps, the paper sensor itself may be faulty or require professional calibration. Contact Lexmark support or a certified technician who can perform remote diagnostics for approximately $49 or provide in-person service. Provide them with the exact error message, your printer model number, and details about when the error started occurring.
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Frequently asked questions
Why does my printer say the paper is too short when I am using standard letter size paper?
This usually happens when the driver is set to a different size than the paper you loaded. For example, if your driver is set to Legal size but you loaded Letter paper, the printer expects a taller sheet and flags the difference. Always check your print settings before sending a job. You can also try resetting the paper size to Auto-Detect in your driver preferences, which tells the printer to measure what is actually in the tray.
Does humidity really cause error 34?
Yes, absolutely. Paper absorbs moisture from humid air, which causes it to swell slightly in thickness and sometimes curl at the edges. When paper curls or changes dimension, the sensor reads it as a shorter sheet than expected. Store paper in a cool, dry place with 40 to 50 percent relative humidity. If you live in a humid climate, keep your paper in an airtight container or resealable bag until you are ready to use it.
Can I still print if I ignore error 34, or do I have to fix it first?
You cannot print while error 34 is active. The printer will not feed paper or process any job until the error is resolved. The error exists as a safety feature to prevent paper jams and damage to your printer. You must clear the error by fixing the underlying paper issue before any printing can resume.
What should I do if cleaning the sensor does not work?
If the sensor is clean and error 34 still occurs, the sensor itself may have failed and need replacement, or the printer firmware may need an update. Visit the Lexmark support website, enter your printer model, and download any available firmware updates. If updates do not help, contact a certified repair technician or Lexmark support, as sensor replacement typically requires professional service and costs between $75 and $150 depending on your model.