Chrome extensions: Use the “background.service_worker” key instead manifest_version 3

Manifest V3 no longer supports background pages. Instead it now supports a new feature called service workers.

The key background in your manifest.json can no longer contain the field persistent, and also update the value from scripts to service_worker. Service worker cannot contain an array but can only contain a single string value.

Eg:

{
  "name": "Test",
  "description" : "Test Chrome Extension",
  "version": "1.0",
  "manifest_version": 3,
  "background": {
    "service_worker": "background.js"
  }
}

Ref: Manifest V3 Migration Checklist