When a printer produces pages of random characters, odd symbols or lines of code, it is printing the raw data it received instead of interpreting it. That almost always means the computer and printer are not speaking the same printer language, or the data was damaged on the way. Common causes are the wrong driver, a corrupted job stuck in the queue, a faulty cable, or a damaged file. This guide starts by clearing the bad job and works toward a clean driver reinstall.
What you might be seeing
- Pages print with random letters, symbols or blocks of code
- Many pages come out with only a line or two of strange text
- Output starts with readable words, then turns into gibberish
- Garbled pages come from only one computer or one app
Common causes
- Wrong driver or printer language
- A driver for another model, or a PostScript driver sending to a printer that only understands PCL, produces raw text output.
- Corrupted print job
- A damaged job in the queue may print as junk and resend after restarts.
- Faulty connection
- A damaged USB cable, loose connection or unstable hub can scramble data in transit.
- Damaged file or font
- A corrupt document or font can send data the printer cannot render.
How to fix it, step by step
Work through these in order and test a print after each one. Most people are done within the first few steps.
Avoid third-party driver download sites, which can install the wrong driver or unwanted software. Use Windows Update, the built-in driver or the manufacturer's official website.
Cancel the job and restart the printer
Turn the printer off at once to stop it wasting paper. On the computer, select the printer in Printers & scanners, choose Open print queue and cancel every job listed. Wait a minute, then switch the printer back on so its memory is cleared. Then try a short test from Notepad or another plain text editor. If that prints correctly, the original document or app is the likely source.
Clear the spooler if jobs will not delete
If jobs stay stuck, press Windows + R, type
services.mscand press Enter. Right-click Print Spooler and choose Stop. In File Explorer, openC:\Windows\System32\spool\PRINTERSand delete the files inside, but not the folder itself. Back in Services, right-click Print Spooler and choose Start. This removes damaged job files that would otherwise keep printing junk.Check the cable and connection
For a USB printer, plug it directly into a port on the computer rather than a hub, docking station or front panel port, and try a different cable if you have one. Shorter cables are more reliable. Network printers rarely garble data because of cabling, but confirm the connection is stable and that no other computer is sending it jobs with the wrong driver.
Confirm the driver matches your printer
Select the printer in Printers & scanners and open Printer properties. The General tab shows the model name the driver was installed for, and the Advanced tab shows the Driver in use. If either names a different model, that explains garbled output. A common mismatch is a PostScript driver used with a printer that only supports PCL, or the reverse.
Change the spooling options
In Printer properties, open the Advanced tab and select Spool print documents so program finishes printing faster, then Start printing after last page is spooled. Avoid Print directly to the printer, which can corrupt jobs from some apps. Select Apply and test again. Spooling the whole job first gives the printer one complete, consistent data stream.
Test another document and app
Print a different file from a different program. If only one document prints garbled, the file may be damaged or use a font the printer cannot handle; try saving it as a PDF and printing that. Some PDF viewers include a print as image option in their advanced settings, which sends the page as a picture and sidesteps font problems. If everything prints garbled, focus on the driver.
Remove and reinstall the driver cleanly
Remove the printer from Printers & scanners. Press Windows + R, type
printui /s /t2and press Enter to open the Drivers tab of Print Server Properties. Select the old driver, choose Remove, then Remove driver and driver package. Restart, and add the printer again using Windows Update or the full driver for your exact model from the manufacturer's official website.
How to keep it from happening again
- Install drivers only from Windows Update or the manufacturer's official website
- Connect USB printers directly to the computer
- Keep spooling turned on in printer properties
- Restart the printer after cancelling a corrupted job
Common questions
Why does my printer print pages of code when nobody is printing?
Unexpected pages of code often come from another computer or device on the network sending jobs with the wrong driver, or from an old job resent when a device reconnects. Check each computer that uses the printer, clear their print queues, and make sure each one uses the correct driver for your model.
What are PCL and PostScript?
They are printer languages: sets of instructions that describe a page. Many business laser printers understand both, while many home inkjets rely on the manufacturer's driver or driverless standards such as IPP Everywhere, AirPrint and Mopria. When a printer receives a language it does not understand, it often prints the instructions as plain text.
Can garbled printing happen on a Mac?
Yes, though it is less common because macOS often uses AirPrint, which sends pages in a format the printer is designed to accept. If a Mac prints gibberish, open System Settings › Printers & Scanners, remove the printer, then add it again and choose AirPrint or the correct model driver from the Use menu.
This guide is general information written for common home and office printers. Menus and button names vary between models, so check your printer’s manual where a step differs. Printer Problems Solved is independent and not affiliated with any printer manufacturer. See our disclaimer.