How to Fix Connection Errors with USB Printers in Jarbas Web (Windows)

How to Fix Connection Errors with USB Printers in Jarbas Web (Windows)

If the USB printer does not work in Jarbas Web after selecting it and trying to print, Windows is usually using a driver that does not allow access via WebUSB. The fix is to change the printer driver to WinUSB using the Zadig software.

When this article applies

Use this procedure if:

  1. you are using Jarbas Web;
  2. you are on Windows;
  3. the printer is USB;
  4. the browser detects the printer but fails to connect or print;
  5. a connection error message appears.

Before you start

  1. Use a Chromium-based browser (e.g., Google Chrome or Microsoft Edge).
  2. Connect the printer directly to the computer’s USB port (avoid hubs if possible).
  3. Close other programs that might be using the printer.
  4. You will need Windows administrator permissions.

Warning: changing the driver may affect how the printer works in other programs (e.g., the manufacturer’s official driver).
If this happens, see the section How to revert to the original driver at the end.

Step-by-step (Zadig)

1) Download Zadig

  1. Go to: https://zadig.akeo.ie
  2. Download the latest version.
  3. Run Zadig as administrator (Run as administrator).

2) Show all USB devices

  1. In Zadig, click Options.
  2. Check List All Devices.

3) Select the correct printer

  1. In the device selection field, choose your USB printer.
  2. Carefully confirm the name/model to avoid changing the driver of another device.

4) Change the driver to WinUSB

  1. On the right side, select WinUSB as the new driver.
  2. Click Replace Driver (or Install Driver).
  3. Wait for the installation to complete.

5) Reconnect and test in Jarbas

  1. Disconnect and reconnect the USB printer.
  2. Close and reopen the browser.
  3. Access Jarbas Web.
  4. Go to the print function and allow access to the USB device when prompted.

Validation (how to confirm it worked)

  1. Jarbas should be able to list/connect to the printer without an Access Denied error.
  2. The test print should work normally.
  3. On first access, the browser may request USB permission (accept it).

How to revert to the original driver (if needed)

If another system stops printing after switching to WinUSB:

  1. Open Windows Device Manager.
  2. Find the printer (under Printers / USB devices).
  3. Right-click > Update driver.
  4. Choose the manufacturer’s driver (or reinstall the official printer driver).
  5. Restart the computer and test again.

Common issues and solutions

Printer does not appear in Zadig

  1. Check the USB cable/port.
  2. Try a different USB port.
  3. Make sure Options > List All Devices is enabled.

Error installing driver in Zadig

  1. Run Zadig as administrator.
  2. Check for IT policies/antivirus blocking driver installation.

Connection error persists in Jarbas

  1. Restart the browser and computer.
  2. Test on an updated Chrome/Edge browser.
  3. Remove USB permissions for the site and grant them again.

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