MV3 Extension not working

[muwave]

I’ve created a very simple test extension using manifest V3 that works in chrome

manifest.json:

{
  "manifest_version": 3,
  "name": "test",
  "version": "0.0.1",
  "content_scripts": [
    {
      "matches": ["*://*/*"],
      "js": ["content.js"]
    }
  ]
}

content.js:

alert('test')

I tried running

web-ext run --firefox-preview

A browser window opens, but the extension is not working…
Using the --verbose option I find these errors

 Firefox stderr: [Parent 14212, IPC I/O Parent] WARNING: file /builds/worker/checkouts/gecko/ipc/chromium/src/base/process_util_win.cc:167
 Firefox stderr: JavaScript error: resource://gre/modules/XULStore.jsm, line 58: Error: Can't find profile directory.
 Firefox stdout: console.error: services.settings:
 Firefox stdout: main/whats-new-panel Signature failed  InvalidSignatureError: Invalid content signature (main/whats-new-panel)
 Firefox stdout: console.error: services.settings:
 Firefox stdout: main/whats-new-panel local data was corrupted
console.warn: services.settings: main/whats-new-panel Signature verified failed. Retry from scratch

 Firefox stdout: console.error: services.settings:
 Firefox stdout: main/addons-manager-settings Signature failed again InvalidSignatureError: Invalid content signature (main/addons-manager-settings)
 Firefox stdout: console.error: services.settings:
 Firefox stdout: Message: InvalidSignatureError: Invalid content signature (main/addons-manager-settings)
  Stack:
    InvalidSignatureError@resource://services-settings/RemoteSettingsClient.jsm:169:5
_validateCollectionSignature@resource://services-settings/RemoteSettingsClient.jsm:977:13

Also if I change the manifest version to 2 the extension works even in Firefox… what am I doing wrong?

[juraj.masiar]

Host permissions now needs to be granted by the user manually for each page… or something like that:

[Blog post] Manifest v3 in Firefox: Recap & Next Steps

I think we chatted about this over matrix, but the issue is about host permissions, in MV3, they’re not granted automatically on install, but instead user needs to grant them at some point. Depending on what’s appropriate for your extension, you could ask the user using promise.request() , or they can grant it by going to about:addons, selecting your addon, and flipping the toggle in the permissions tab. We’re also working on an easier UI to do this, tied to your extension browser action, but…

See also:

Making host permissions optional by default appears to be harmful for extensions with global host permissions

[Robert_Uomini]

I’m not seeing any permissions tab; at least, tapping “Permissions” doesn’t prompt me for anything. It just takes me to a link “Learn about permissions”.

[juraj.masiar]

That applies only to desktop Firefox.

Firefox for Android is a bit “behind” regarding addons support .

[Robert_Uomini]

Any idea when we can expect add-ons for Android Firefox to be ready for testing? As you can imagine, my users are clamoring for a mobile solution.

[juraj.masiar]

Can’t say, but the MV2 addons are allowed in Beta version, although it’s more like a “workaround”, so not suitable for normal users.

See for example this article:
https://www.ghacks.net/2022/10/20/firefox-beta-for-android-now-supports-custom-add-on-collections/

[Robert_Uomini]

Thanks for the link. Unfortunately, it didn’t help much because my extension is brand new and therefore isn’t in the add-ons store, hence it doesn’t have a collection ID (if you can all a single extension a “collection”).