◆Error Codes Wiki

WebUSB Access Denied — Browser USB Device Connection and Permission Errors

Informationalgeneral

Overview

Fix WebUSB API access denied errors when websites cannot connect to USB devices due to permission issues, driver conflicts, or browser restrictions.

Key Details

  • WebUSB allows websites to communicate with USB devices directly from the browser
  • It requires HTTPS, user gesture, and explicit user permission via a device chooser dialog
  • Only Chromium-based browsers support WebUSB — Firefox and Safari do not
  • Some USB devices are blocked by default: HID keyboards/mice, mass storage, smart cards
  • OS-level drivers may claim the USB device, preventing WebUSB from accessing it

Common Causes

  • User denied USB device access when the permission dialog appeared
  • USB device is claimed by an OS driver preventing browser access
  • Device is in the WebUSB blocklist (HID devices, storage devices are blocked for security)
  • Browser does not support WebUSB (Firefox, Safari, all iOS browsers)

Steps

  1. 1Click the website's 'Connect' button (user gesture required) and select the device from the chooser dialog
  2. 2Check if the device needs a driver release: on Linux, may need udev rules; on Windows, may need Zadig
  3. 3Verify the device is not on the blocklist: HID keyboards, mice, and mass storage are blocked
  4. 4Use Chrome (or Edge) as the browser — Firefox and Safari do not support WebUSB
  5. 5For development: test with chrome://usb-internals/ to see connected devices and their descriptors

Tags

webusbusbpermissiondeviceapi

Related Items

browser-web-bluetooth-device-not-found

More in General

printer-offlinePrinter Offline Error
Warning
driver-unavailablePrinter Driver Is Unavailable
Warning
spooler-errorPrint Spooler Error
Warning
pcl-xl-errorPCL XL Error — Subsystem Kernel
Warning
printer-duplex-printing-errorsPrinter Duplex (Double-Sided) Printing Errors — Jams, Alignment & Blank Pages
Warning
printer-usb-connection-errorsUSB Printer Errors — Not Detected, Driver Issues, and Connection Troubleshooting
Warning

Frequently Asked Questions

Custom USB devices, Arduino boards, 3D printers, scientific instruments, and similar devices with standard or vendor-specific USB interfaces. Blocked: keyboards, mice, webcams, storage devices, smart cards, and other devices with potential security implications.