There was an error during installation: Extension is invalid - Adapting chrome extension into firefox

I'm adapting a google-chrome extension into firefox.

This extension is fairly simple, it just reloads current browser window and places a specific string into it (It is used to activate a debugging state on Odoo).

However, when I test it agaisnt the mozilla test site, it says the test has passed and the extension should be ready to go.

But everytime I try on my browser on about:debugging erss, it throws the same thing over and over again.

Just updated the browser to version 57.0 and the same story goes on.

This is my directory structure (I've added the addon to a zip file)

 background.js
 LICENSE
 manifest.json
 off.png
 on.png
 README.md
 super_on.png

My manifest file:

{
"name": "My Debug",
"version": "3.3",
"manifest_version": 2,
"description": "Toggle debug mode",
"short_name": "My Debug",
"offline_enabled": true,
"browser_action": {
    "default_icon": "off_.png",
    "default_title": "- Click for Debug \n- Double Click for Debug"
},
"applications": {
      "id": "email@email.com"
},
"incognito": "spanning",
"background": {
    "scripts": ["background.js"]
},
"permissions": ["activeTab", "webNavigation", "*://*/*", "tabs"],
"icons": {
    "16": "off.png",
    "128": "off.png"
}
}

It throws me:

There was an error during installation: Extension is invalid

I know the install.rdf isn't needed anymore.

Maybe some error on manifest file?