Chrome Extension upload error - default_locale missing

Question

Whenever I try to upload my updated extension to the Chrome Web Store I get a "default_locale field is missing in manifest." error, yet it is clearly located in my manifest (pasted below).

Any pointers for how I can resolve this?

{
  "manifest_version": 2,
  "name": "####",
  "version": "1.1.0",
  "default_locale": "en-US",
  "description": "####",
  "icons": {
    "16": "icons/icon16.png",
    "48": "icons/icon48.png",
    "64": "icons/icon64.png",
    "128": "icons/icon128.png"
  },
  "homepage_url": "http://####.com",
  "permissions": [
    "https://*.####.com/*",
    "https://####.com/*"
  ],
  "content_scripts": [
    {
      "matches": [
        "https://*.####.com/*",          
        "https://####.com/*"
      ],
      "css": [
        "src/####/####.css"
      ]
    }
  ]
}

Answer 1

It seems the Web Store wanted a _locales directory added to the root with subfolders ("en_US" for my case) and accompanied by properly setup messages.json files. Following the information from the Localizing your app guide resolved the issue.

Hoping Google can change their error message be something like "_locales directory not found" rather than the manifest error we currently receive.