Mv2 to Mv3 Checklist

Manifest Transition Checklist

Paste your MV2 manifest.json below to see what needs to be changed to make it compatible with MV3

1{
2  "name": "Plasmo Sample Manifest",
3  "description": "Paste your MV2 manifest.json here",
4  "manifest_version": 2,
5  "icons": {
6    "16": "icons/icon-16.png",
7    "48": "icons/icon-48.png",
8    "128": "icons/icon-128.png"
9  },
10  "default_locale": "en",
11  "background": {
12    "scripts": [
13      "background1.js",
14      "background2.js",
15      "background3.js"
16    ]
17  },
18  "permissions": [
19    "storage",
20    "https://www.plasmo.com/*",
21    "https://itero.plasmo.com/*",
22    "https://plasmo.com/s/d",
23    "https://*/*",
24    "file://*/*"
25  ],
26  "browser_action": {
27    "default_popup": "popup.html"
28  }
29}

{
  "name": "Plasmo Sample Manifest",
  "description": "Paste your MV2 manifest.json here",
  "manifest_version": 2,
  "icons": {
    "16": "icons/icon-16.png",
    "48": "icons/icon-48.png",
    "128": "icons/icon-128.png"
  },
  "default_locale": "en",
  "background": {
    "scripts": [
      "background1.js",
      "background2.js",
      "background3.js"
    ]
  },
  "permissions": [
    "storage",
    "https://www.plasmo.com/*",
    "https://itero.plasmo.com/*",
    "https://plasmo.com/s/d",
    "https://*/*",
    "file://*/*"
  ],
  "browser_action": {
    "default_popup": "popup.html"
  }
}

4 Issues Found in Manifest

Autofix

Unified Action API

Browser action and Page action are replaced by the Action API
Use declarativeContent API to show the action only on specific pages

Background Service Worker

Background Scripts are replaced by a single Background Service Worker
Background Service is not persistent and will be stopped after 5 minutes
Adapt to the service worker execution context, and persist data using the storage API

Host Permissions is Separated

Any permissions related to accessing remote locations are now separated into host_permissions

File URL Permission Notes

The user must visit the extension management page and opt-in to file access

About Plasmo Manifest Transition Checklist

Manifest Version 3, or MV3 for short, introduces many semantic and architectural changes that developers need to understand to transition to the new version. Background pages are no longer persistent, and are substituted for service workers that live for a maximum of 5 minutes. Keys are restructured, and permissions are more granular.

Instead of relying on documentation that might discuss things unrelated to your project, the Plasmo Manifest Checklist tells you exactly what you need to know to go from MV2 to MV3. We are releasing this tool for free in hopes that it will help developers transition to MV3 more easily.

Looking for More?

MV2 Config Converter

Transform your manifest.json file to MV3 with one click

Skip the manual work and crawling pages of unrelated documentation, let Itero converts your manifest.json file to MV3 automatically. Quickly get started with MV3 development and focus on your crucial business logic.

MV2 Bundle Code Scanner

Scan your entire extension for problematic MV2 issues

Instead of manually digging through your codebase, Itero automatically identifies key issues you need to solve when migrating to MV3, and presents elegant solutions to make the process as seamless as possible.