HP Printer Error Code 84 — What It Means & How to Fix It

What Does This Error Mean?

Error 84 means your HP printer cannot communicate with its optional lower paper tray unit. This accessory tray connects to the bottom of the printer to hold extra paper. The error usually means the tray is not attached properly or the connector between them has an issue.

Affected Models

HP LaserJet 4100
HP LaserJet 4200
HP LaserJet 4250
HP LaserJet 4300
HP LaserJet 4350
HP LaserJet 5200

Common Causes

The optional lower tray unit is not fully seated against the base of the printer
The electrical connector between the printer and the lower tray has come loose
The connector pins on the tray or printer have become dirty or corroded
The lower tray unit itself has developed an internal fault
The printer's firmware does not recognize this particular tray model

How to Fix It

Turn off the printer and disconnect the power cord. Carefully lift the printer off the optional lower tray unit.

Most HP LaserJet optional trays attach via a mechanical docking system and an electrical connector on the bottom of the printer.
Inspect the electrical connector on both the bottom of the printer and the top of the tray unit. Look for bent pins, debris, or corrosion.

Even a single bent pin can prevent communication between the printer and the tray.
Clean both connectors with a dry cotton swab or lint-free cloth to remove any dust or oxidation.

Do not use liquid cleaners on the electrical connectors.
Carefully lower the printer back onto the tray unit, making sure the connectors line up and the unit locks into place securely.

You should feel the printer settle firmly onto the tray without wobbling. Reconnect the power and turn the printer on.
If the error continues, try running the printer without the optional tray by placing it directly on a desk. If it works without the tray, the tray unit is the source of the fault.

Print from the printer's built-in tray (Tray 1 or Tray 2) as a workaround while you arrange a replacement tray.

When to Call a Professional

Error 84 is a hardware configuration issue. If reseating the tray does not help, the connector or tray unit may need professional inspection. HP authorized technicians can test and replace faulty tray units and connectors. Optional tray units can sometimes be found secondhand from printer resellers.

Frequently Asked Questions

Can I still print if I get error 84?

Often yes — you can still print from the printer's built-in paper trays. Error 84 only affects the optional lower tray unit. Just disconnect the optional tray and use the standard trays until the issue is resolved.

Are optional lower trays expensive to replace?

New optional trays from HP can be expensive — sometimes $100 to $300 depending on capacity. However, used trays from the same printer family can be found on eBay for $20 to $60. Make sure the tray model is listed as compatible with your specific printer model number.

Does the optional tray need its own power cable?

No. HP optional lower tray units are powered through the connector that links them to the printer. There is no separate power cable for the tray. This is why a clean, well-connected electrical connector is so important for the tray to function.