Issue 1:
Preflight Checklist

I have read the Contributing Guidelines for this project.

I agree to follow the Code of Conduct that this project adheres to.

I have searched the issue tracker for an issue that matches the one I want to file, without success.

Issue Details

Electron Version:

10.1.3

Operating System:

macOS 10.15.7

Last Known Working Electron version:

8.5.2

Expected Behavior

In my project I am loading ReactDevTool.

app.whenReady().then(async () => {
await createWindow();
await session.defaultSession.loadExtension(path.join(os.homedir(), extPath));
});

In the terminal for version 10.1.3 we see warnings:

(node:6207) ExtensionLoadWarning: Warnings loading extension at /Users/foobar/Library/Application Support/Google/Chrome/Default/Extensions/fmkadmapgofadopljbjfkapdkoienihi/4.8.2_0:
Unrecognized manifest key 'browser_action'.
Unrecognized manifest key 'minimum_chrome_version'.
Unrecognized manifest key 'update_url'.
Manifest contains a differential_fingerprint key that will be overridden on extension update.
Cannot load extension with file or directory name _metadata.
Filenames starting with "_" are reserved for use by the system.

And the extension doesn't work.

Actual Behavior

With warnings: ExtensionLoadWarning, no extension working.

To Reproduce

$ git clone git@github.com:electron/electron-quick-start.git
$ cd electron-quick-start
$ npm install

and edit main.js

// Modules to control application life and create native browser window
const { app, BrowserWindow, session } = require('electron');
const os = require('os');
const path = require('path');

const extPath =
'/Library/Application Support/Google/Chrome/Default/Extensions/fmkadmapgofadopljbjfkapdkoienihi/4.8.2_0';

async function createWindow() {
// Create the browser window.
const mainWindow = new BrowserWindow({
width: 800,
height: 600,
webPreferences: {
preload: path.join(__dirname, 'preload.js'),
},
});

// and load the index.html of the app.
await mainWindow.loadFile('index.html');

// Open the DevTools.
mainWindow.webContents.openDevTools({ mode: 'detach' });
}

// This method will be called when Electron has finished
// initialization and is ready to create browser windows.
// Some APIs can only be used after this event occurs.
app.whenReady().then(async () => {
await createWindow();
await session.defaultSession.loadExtension(path.join(os.homedir(), extPath));
});

// Quit when all windows are closed, except on macOS. There, it's common
// for applications and their menu bar to stay active until the user quits
// explicitly with Cmd + Q.
app.on('window-all-closed', function () {
app.quit();
});

Issue 2:
Preflight Checklist

I have read the Contributing Guidelines for this project.

I agree to follow the Code of Conduct that this project adheres to.

I have searched the issue tracker for an issue that matches the one I want to file, without success.

Issue Details

Electron Version:

v9.0.0

Operating System:

macOS 10.15.4

Last Known Working Electron version:

8.2.0

Expected Behavior

In our project we are loading ReactDevTool and ReduxDevTools.

app.on('ready', async () => {
await session.defaultSession.loadExtension(
path_to_devtools
);
});

In the terminal for version 9.0.0 we see warnings:

(node:59148) ExtensionLoadWarning: Warnings loading extension at path_to_ext: Unrecognized manifest key 'browser_action'. Unrecognized manifest key 'minimum_chrome_version'. Unrecognized manifest key 'update_url'. Cannot load extension with file or directory name _metadata. Filenames starting with "_" are reserved for use by the system.
(node:59148) ExtensionLoadWarning: Warnings loading extension at path_to_ext: Unrecognized manifest key 'browser_action'. Unrecognized manifest key 'minimum_chrome_version'. Unrecognized manifest key 'update_url'. Cannot load extension with file or directory name _metadata. Filenames starting with "_" are reserved for use by the system.
(node:59148) ExtensionLoadWarning: Warnings loading extension at path_to_ext: Unrecognized manifest key 'commands'. Unrecognized manifest key 'homepage_url'. Unrecognized manifest key 'page_action'. Unrecognized manifest key 'short_name'. Unrecognized manifest key 'update_url'. Permission 'notifications' is unknown or URL pattern is malformed. Permission 'contextMenus' is unknown or URL pattern is malformed. Permission 'tabs' is unknown or URL pattern is malformed. Cannot load extension with file or directory name _metadata. Filenames starting with "_" are reserved for use by the system.
(node:59148) ExtensionLoadWarning: Warnings loading extension at path_to_ext: Unrecognized manifest key 'commands'. Unrecognized manifest key 'homepage_url'. Unrecognized manifest key 'page_action'. Unrecognized manifest key 'short_name'. Unrecognized manifest key 'update_url'. Permission 'notifications' is unknown or URL pattern is malformed. Permission 'contextMenus' is unknown or URL pattern is malformed. Permission 'tabs' is unknown or URL pattern is malformed. Cannot load extension with file or directory name _metadata. Filenames starting with "_" are reserved for use by the system.

And both extensions don't work.

Actual Behavior

No warnings in the terminal and working extensions.