my hp m404dn just shows 'scanning for drivers' on the screen and won't print anything

Diagnosis

The "Scanning for Drivers" message on an HP LaserJet Pro M404dn is not actually a printer failure, but a state of "handshake suspension." This occurs when the printer's internal firmware detects a connection to a host computer via the USB port, but the Windows Print Spooler or the HP Smart software fails to send the necessary initialization packet to complete the driver handshake. Essentially, the printer is in a waiting loop, pausing all print jobs until it receives a "Ready" signal from the OS. This most frequently happens after a Windows Update that replaces the native HP driver with a generic "Class Driver," or when the USB cable is plugged into a USB 3.0 (blue) port that is experiencing power-management instability. You can confirm this is a communication hang by attempting to print a "Configuration Page" directly from the printer's onboard menu; if the internal page prints but the computer jobs don't, the hardware is fine and the issue is strictly the software handshake loop.

How to Fix It

To break the driver loop and restore printing functionality, follow these exact steps to reset the communication bridge:

1. Power down the printer completely using the power switch on the rear.
2. Disconnect the USB cable from both the printer and the computer.
3. On the computer, open Device Manager (Right-click Start > Device Manager). Expand the "Printers" or "Other Devices" section. Right-click on any entry labeled "HP LaserJet M404" or "Unknown Device" and select Uninstall Device. Check the box for "Delete the driver software for this device" if prompted.
4. Turn the printer back on. On the printer control panel, press the OK button to enter the menu.
5. Navigate to Settings > General Setup > USB Host Timeout. Change this value from the default 300 seconds to 0 (Infinite). This prevents the printer from timing out while waiting for the computer to respond.
6. Plug the USB cable into a USB 2.0 port (typically black) rather than a USB 3.0 port (blue) to ensure maximum compatibility.
7. Restart the computer. Windows should now trigger the "Found New Hardware" wizard, allowing the printer to complete the handshake and clear the "Scanning for Drivers" message.

If That Didn't Work

• Clear the Print Spooler: The loop may be caused by a corrupted print job stuck in the queue. Press Win + R, type services.msc, find Print Spooler, right-click and select Stop. Navigate to C:\Windows\System32\spool\PRINTERS and delete all files in that folder. Go back to the Services window and Start the Print Spooler.
• Force Manual Driver Installation: Instead of letting Windows "scan," download the HP LaserJet Pro M404dn Full Software and Drivers package directly from the HP support site. Run the installer and select "USB Connection" manually when prompted. This forces the driver to overwrite the generic class driver that is causing the hang.
• Swap the USB Cable: The M404dn is sensitive to cable shielding. If you are using a cable longer than 6 feet (2 meters), the signal attenuation can cause the "Scanning" loop. Replace the current cable with a high-quality, shielded USB 2.0 A-to-B cable with ferrite beads (the small cylinders near the ends).
• Perform a Cold Reset: If the screen is still frozen, turn the printer off. Hold down the Right Arrow and Cancel (X) buttons simultaneously while turning the power back on. Release the buttons when the "Cold Reset" message appears. This wipes the network and USB cache and forces a fresh hardware discovery.

Heads Up

• Avoid using USB hubs or docking stations for this model; plug the printer directly into the motherboard ports on the rear of the PC to avoid voltage drops.
• Disable "USB Selective Suspend" in your Windows Power Options (Control Panel > Power Options > Change plan settings > Advanced power settings > USB settings) to prevent the PC from putting the printer port to sleep.
• Keep the firmware updated via the HP Firmware Update Utility to resolve known handshake bugs in the M404 series.
• If you transition to network printing via Ethernet (the 'dn' model), disable the USB port in the settings to prevent the printer from attempting to scan for drivers on both interfaces simultaneously.