Issue with loading files whitelisted in web_accessible_resources with Manifest v3.

[andrewplummer]

With Chrome 89.0.4389.90
Using manifest v3:

{
  "manifest_version": 3,
  "name": "Positionable!",
  "version": "2.1.0",
  "short_name": "Positionable",
  "description": "An extension for visually manipulating elements in the browser.",
  "offline_enabled": true,
  "icons": {
    "16": "images/app/16.png",
    "32": "images/app/32.png",
    "48": "images/app/48.png",
    "128": "images/app/128.png"
  },
  "permissions": [
    "activeTab",
    "scripting",
    "storage"
  ],
  "background": {
    "service_worker": "worker.js"
  },
  "action": {
    "default_icon": "images/app/16.png",
    "default_title": "Positionable!"
  },
  "web_accessible_resources": [
    {
      "resources": [
        "*.html",
        "*.css",
        "images/app/128.png"
      ],
      "matches": [],
      "extension_ids": []
    }
  ]
}

attempting to load files with fetch:

fetch(chrome.runtime.getURL('element.html'));

throws an error:

Denying load of chrome-extension://hjaobakeiobofnogiplphaggdbfibbfm/element.html. Resources must be listed in the web_accessible_resources manifest key in order to be loaded by pages outside the extension.

This was working fine in v2. I've tried every variation I could to whitelist the files but nothing seems to work.

[dotproto]

Please note that this repository is for issues related to developer.chrome.com. In the future, if you have general questions about writing extensions please post to the chromium-extensions Google Group or on Stack Overflow.

PR #539 aims to update our outdated web accessible resources documentation to reflect the changes in Manifest V3.

The code you provided appears to be working as expected. Your manifest explicitly sets empty matches and extension_ids arrays, so you're effectively telling Chrome not to match anything.

If you want to expose these resources to all pages you can modify your web accessible resources declaration as follows:

  "web_accessible_resources": [
    {
      "resources": [
        "*.html",
        "*.css",
        "images/app/128.png"
      ],
      "matches": [
        "<all_urls>"
      ]
    }
  ]

[andrewplummer]

Thank you, the docs were quite unclear on this one... it seems to have worked.