Basic Issue – Extension can't access Website

Hello forum, I have a noob question:

There is this basic error coming up with all basic extensions I’m testing:

My Extensions "Can’t read and edit Data on this website"

Even this basic tutorial doesn’t work:

I reainstalled Firefox and also deleted all the settings files. Still.

What could it be?

Thanks so much, Kakaoboy

Which page are you testing this on? That example should only work on

Hey @zombie thanks for answering.

I’m testing on all kind of sites. You said, it should only work on

Why is that so?

How can I make it work on all sites?

Thanks for your support.

That example has a content script which only targets

  "content_scripts": [
      "matches": ["*://**"],
      "js": ["borderify.js"]

You can change that using a different match pattern: