Printer keeps printing random characters — driver corruption fix

Joe B.

Reviewed for technical accuracy

Specialities: Windows 11/10, macOS (Sonoma/Ventura/Monterey), Printers, Networking, Office Equipment

Printer printing gibberish / random symbols — HP, Epson, Canon, Brother — PCL vs PS driver mismatch, RAW/IPP issues

Technician

Hey! We’ll stop your printer from printing random characters. Tell me: the brand (HP, Epson, Canon, Brother), your OS (Windows 10, Windows 11, or Mac), and what exactly shows on the page — e.g., @PJL, PCL XL error, %%[ Error: undefined; OffendingCommand ]%%, or just gibberish / weird symbols. These clues point to driver corruption or a PCL vs PostScript mismatch.

Customer

Windows 11 desktop, HP LaserJet. Every time I print a PDF or even a test page I get lines of @PJL commands and random letters. It started after a Windows update. The printer won’t stop spitting pages of garbage text.

Technician

Classic symptoms of a corrupted printer driver or protocol mismatch.
• Windows likely swapped your vendor driver for a Microsoft IPP Class Driver or the wrong PCL/PS flavor.
• When the queue sends raw data the printer can’t parse (PCL XL to a PS-only device, or vice-versa), you get random characters and @PJL header text.
• Spooler/port issues (RAW vs WSD/IPP) can also print weird symbols.
Game plan: purge the stuck job, reset the spooler, remove the class driver, and reinstall the correct HP LaserJet driver (PCL6 or PS) — then test with a clean print.

Customer

How do I clear the endless job and reset the Windows print spooler? The printer keeps printing symbols even after I hit Cancel.

Technician

Clear garbage text & reset spooler — Windows 10/11:
1) Unplug the printer’s USB/Ethernet (or turn it off) to stop new pages.
2) Press Win+R → type services.msc → right-click Print Spooler → Stop.
3) Go to C:\Windows\System32\spool\PRINTERS and delete everything (these are the stuck jobs).
4) Start the Print Spooler service again. Reconnect the printer.
5) In Settings → Bluetooth & devices → Printers & scanners, remove the current queue if it’s using Microsoft IPP Class Driver.
6) Install the manufacturer’s package (HP Smart/Full Feature) and pick the correct PCL6 or PostScript driver. For many LaserJets, HP PCL-6 (v4) is ideal.

Customer

After reinstalling, should I use USB, TCP/IP, WSD, or IPP? I’ve seen “WSD port” cause problems.

Technician

Good question. For reliability and to avoid random characters:
• Network printers: create a Standard TCP/IP Port to the printer’s static IP (RAW 9100). Avoid WSD unless you must.
• USB printers: let the vendor installer create the port.
• IPP works, but Windows may pick a Class Driver that doesn’t match your device language. RAW over TCP/IP + vendor driver is the most predictable.

Customer

What about Mac? My MacBook prints strings like “%!PS-Adobe” or random PostScript codes.

Technician

Fix printer printing gibberish on macOS:
• System Settings → Printers & Scanners → select the printer → remove it.
• Re-add with AirPrint if your model supports PostScript/PCL via IPP. If features are missing, install the vendor package (HP, Canon, Brother, Epson) and choose that driver.
• If you still see “%!PS-Adobe” on the page, you’re sending PS to a PCL-only device — switch the queue to PCL (or the reverse). Print a 1-page PDF to confirm.

Customer

How do I pick between PCL and PostScript? And what is “Universal Print Driver”?

Technician

• PCL6: fast, highly compatible with HP/Brother/Canon laser printers. Great default for office docs; fewer PCL XL error pages when matched correctly.
• PostScript (PS): best for complex graphics/Adobe workflows; some models require a PS add-on.
• Universal Print Driver (UPD): a vendor package (HP/Brother/Canon) that supports many models. Choose the UPD PCL6 or PS variant that your printer speaks. A mismatch is a common cause of printer prints random characters.

Customer

The issue comes back after every Windows Update. Any way to stop Windows from switching back to the IPP Class Driver?

Technician

You can reduce swaps:
• After installing the correct vendor driver, open Control Panel → Devices and Printers → set it as Default and remove the class-driver queue.
• Optional: in System → Advanced system settings → Device Installation Settings, choose not to automatically download vendor apps/drivers.
• In managed environments, use Group Policy/Intune to push the right package and Standard TCP/IP port.

Customer

Are there app-specific causes? We see gibberish from Word and also from Adobe Acrobat.

Technician

• Acrobat/Reader: try Print as image once to verify the pipeline. If that works, the driver language is mismatched — reinstall with the proper PCL/PS flavor.
• Word/Office: in Printer Properties disable advanced features like Enable advanced printing features temporarily; test again.
• Browsers/Google Docs: use the System Dialog (Ctrl+Shift+P/Cmd+Option+P) to make sure you’re targeting the vendor queue, not the class driver.

Customer

If I can’t get drivers right away, is there a temporary way to stop the garbage text?

Technician

Yes — quick mitigations:
• Print via Microsoft PDF first, then print that PDF from the vendor queue.
• On macOS, toggle AirPrint vs vendor driver to see which language your device accepts.
• For USB, try another cable/port (bad USB signaling can corrupt job data). But the permanent fix is still reinstall the correct printer driver.

Customer

Great — the random symbols are gone after I installed HP PCL-6 and set a TCP/IP port. Thanks!

Technician

Summary: When a printer keeps printing random characters, the cause is almost always driver corruption or a PCL vs PostScript mismatch. Clear the spooler, remove class drivers, install the correct vendor driver (HP/Epson/Canon/Brother), and use a Standard TCP/IP (RAW 9100) port. Need hands-on help? Open the chat.

Quick answer: the accepted fix

Accepted fix when printer prints random characters / gibberish (Windows 10/11 or macOS): Stop and clear the Print Spooler, remove the IPP/Class queue, then reinstall the correct vendor driver (PCL6 or PostScript). Create a Standard TCP/IP port (RAW 9100), print a test PDF, and confirm the printer language matches to prevent garbage text.

FAQ

Step-by-step (Windows 10/11)

1. Disconnect printer → stop Print Spooler → clear spool\PRINTERS → start spooler.
2. Remove the class/incorrect queue. Install the brand’s Full Feature/Universal package.
3. Create a Standard TCP/IP port (RAW 9100) for network models.
4. Choose the correct language: PCL6 or PostScript. Print a 1-page PDF test.

Step-by-step (macOS)

1. Remove the printer in System Settings → Printers & Scanners.
2. Re-add using AirPrint or the vendor driver that matches your device language.
3. Print a test PDF; if text like “%!PS-Adobe” appears, switch the driver language.

Sources

• Microsoft — Troubleshoot printer problems (Windows 10/11)
• Apple — Print from your Mac
• HP — Drivers & Software
• Brother — Full Driver & Software Package
• Canon — UFR II / PS drivers
• Epson — Drivers & Utilities

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