HP Printer Error Code 79 – Meaning, Causes & Fix
HP printer error code 79 is a critical firmware or service error that appears on HP LaserJet, OfficeJet, and enterprise printers when the printer's firmware encounters a fatal exception it cannot recover from on its own. The error causes the printer to halt all operations and display '79 Service Error' or '79.XXXX Error' on the control panel. Unlike paper jams or ink errors, error 79 is a software-level fault — it is typically triggered by a corrupted print job, incompatible firmware, a bad network packet, or a defective accessory that confuses the printer's processing system. In the majority of cases, error 79 is fully resolvable without any hardware replacement. This guide covers every known cause, the exact steps to clear it, and when the error points to a deeper hardware problem. Users dealing with other HP printer faults may also want to check our HP Printer Cartridge Problem error guide for related diagnostics.
What it means
HP printer firmware has encountered a fatal exception and cannot continue. Usually caused by a corrupted print job, bad firmware, or incompatible accessory.
Severity
HighCan you fix it yourself?
Yes — power cycling and clearing the print queue resolves most 79 errors without any hardware repair.
Call a technician when
Contact HP Support if error 79 persists after power cycling, clearing the queue, and reinstalling firmware.
What Does 79 Mean?
HP error code 79 is a firmware-level critical error, sometimes described as a 'service error' in HP's internal documentation. It occurs when the printer's embedded firmware encounters an unhandled exception — a situation the firmware code was not programmed to handle gracefully.
The '79' prefix refers to HP's internal error class for critical firmware faults. The four-digit suffix that follows (e.g., 79.0000, 79.0004, 79.00FE) gives HP service technicians additional diagnostic information, but for end users, all 79.XXXX codes are treated the same way.
Common triggers:
1. Corrupted print job: A malformed PDF, PostScript file, or print job with unsupported encoding crashes the firmware's rendering pipeline. 2. Incompatible firmware version: A firmware update that is not fully compatible with the specific printer model or installed accessories. 3. Third-party accessories: An incompatible EIO card, DIMM memory module, or hard drive accessory sending unexpected data. 4. Bad network packet: A malformed network print request (especially PostScript) triggering a firmware exception. 5. Corrupted firmware: Firmware that was partially updated (due to power interruption) and is now in a corrupted state. 6. Control board fault: In rare cases, a failing formatter board causes persistent 79 errors.
Error 79 is related to other HP firmware faults — see our HP Printer Cartridge Problem error guide for comparison. If you're troubleshooting Canon printer firmware errors, our Canon Printer Error 5B00 guide and Canon Printer Support Code 6000 guide cover similar critical fault patterns on Canon hardware.
What Causes This Error?
- Corrupted or malformed print job (PDF, PostScript, or XPS file) crashing the firmware
- Incompatible or partially installed firmware update
- Third-party EIO card, DIMM module, or hard drive accessory incompatible with the printer
- Malformed network print request triggering a firmware exception
- Firmware corrupted by power loss during an update
- USB or network connection sending malformed data packets
- Formatter (controller) board hardware failure causing persistent 79 errors
- Incompatible printer driver sending unsupported commands
How to Fix 79
- 1
Power cycle the printer completely. Turn the printer off using its power button. Unplug the power cord directly from the back of the printer (not just from the wall outlet). Wait a full 60 seconds — this ensures all residual charge drains from the formatter board and all error states are cleared from memory. Plug the power cord back in directly to the wall outlet (not a surge protector or UPS, which can filter voltage). Power on the printer and wait for it to complete its full initialization cycle before attempting to print.
- 2
Clear all jobs from the print queue. On your computer, open the print queue (Control Panel > Devices and Printers > right-click your HP printer > See what's printing). Cancel and delete every pending job. A single corrupted job at the front of the queue will cause error 79 every time the printer is powered on and reconnects. After clearing the queue, power cycle the printer again and attempt a test print using the printer's own built-in test page (accessible from the control panel menu).
- 3
Remove all accessories and optional components. Turn the printer off and unplug it. Remove any third-party accessories: EIO cards (installed in the EIO slots on the back of the printer), additional DIMM memory modules, optional hard drives, and any additional paper trays. These components can trigger error 79 if they are incompatible or defective. Power the printer on with only its base configuration. If error 79 clears, add components back one at a time to identify the culprit.
- 4
Update or reinstall the printer firmware. Visit hp.com/support and search for your exact printer model. Download the latest firmware package. Install it following HP's instructions — do not interrupt the process. If the printer was running an older firmware version, the update resolves many 79 errors caused by known firmware bugs. If you suspect the current firmware is corrupted, reinstalling the same version (clean install) can also resolve the issue.
- 5
Reset the printer to factory defaults. On the printer's control panel, navigate to Settings > Service > Restore Factory Defaults (the exact menu path varies by model — consult your model's manual). A factory reset clears all custom settings, stored jobs, and configuration data that may have become corrupted. Note: this will also reset network settings, IP address, and user configurations — document these before resetting.
- 6
Test with a direct USB connection and simple document. If the printer is connected via network, switch to a direct USB connection for testing. Send a simple plain-text document (not a complex PDF) to the printer. If the printer handles the USB test job successfully but fails over the network, the issue is a network-side configuration problem — review your network settings and consider updating your print driver.
When to Call a Professional
HP error 79 that persists after power cycling, clearing the print queue, removing accessories, and reinstalling firmware indicates a failed formatter (controller) board. The formatter is the main processing board of the printer and handles all print job rendering. Formatter board replacement requires a trained HP technician and is typically not cost-effective on older or entry-level printers. Contact HP support at support.hp.com or 1-800-474-6836. For enterprise HP LaserJet printers, HP provides on-site service options under support contracts. Formatter board replacement cost ranges from $150–$600 depending on model.
Can You Still Use the Device?
The printer cannot process any print jobs while error 79 is displayed. All printing functions are halted. However, the printer itself is not damaged by this error state — it is a safety halt to prevent data corruption. Once the error is cleared through the steps above, the printer will resume normal operation.
See Also
Official Resources
Related Error Codes
Disclaimer: This article is for informational purposes only and does not constitute professional repair advice. CodeExplain is not affiliated with HP or any other brand mentioned. Always consult a qualified technician for complex repairs.