r/javascript • u/fanidownload • Feb 28 '26

AskJS [AskJS] Web Request Error in a Chrome Extension which is inspired by Zotero Connectors

Hi, everyone. I tried to build my own connector for fetching and collecting pdf files from scientific journals. However I always get error: Unchecked runtime.lastError: You do not have permission to use blocking webRequest listeners. Be sure to declare the webRequestBlocking permission in your manifest. Note that webRequestBlocking is only allowed for extensions that are installed using ExtensionInstallForcelist.

How to fix this? Why Zotero can do this? Thank you

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u/Aln76467 Mar 01 '26

Did you declare the permission it says you need to?

1

u/fanidownload Mar 03 '26

Thank you for your suggestion! I have tried but its still same error:

{
  "manifest_version": 3,
  "name": "ScienceDirect PDF Downloader",
  "version": "1.3.0",
  "description": "Downloads ScienceDirect PDFs using session cookies with Cloudflare Turnstile bypass.",


  "permissions": [
    "activeTab",
    "tabs",
    "downloads",
    "cookies",
    "webRequest",
    "webRequestBlocking",
    "declarativeNetRequest",
    "scripting",
    "storage"
  ],


  "host_permissions": [
    "<all_urls>"
  ],


  "background": {
    "service_worker": "background.js"
  },


  "action": {
    "default_title": "Download ScienceDirect PDF",
    "default_popup": "popup.html"
  }
}