Laravel Socialite Facebook 登录错误：参数 app_id 是必需的

试图让社交名流使用我的应用程序。 Facebook 返回The parameter app_id is required error.

Routes:

Route::get('/login/facebook', '\CommendMe\Http\Controllers\AuthController@redirectToProvider');

Route::get('/login/facebook/callback', '\CommendMe\Http\Controllers\AuthController@handleProviderCallback');

服务.php:

'facebook' => [
    'client_id' => env('426129694395672'),  
    'client_secret' => env('840fca14fc9fac4b592cd49f285c2ee9'), 
    'redirect' => 'http://localhost/login/facebook/callback',
],  

AuthController.php

public function redirectToProvider() {
    return Socialite::driver('facebook')->redirect();
}   

public function handleProviderCallback() {
    $user = Socialite::driver('facebook')->user();

    $user->name;
}   

当尝试/login/facebook路线，facebook 返回此错误。 为什么会发生这种情况？

要么用作

'client_id' => '426129694395672',  

Or

'client_id' => env("FB_APP",'426129694395672'),  

and use FB_APP = '426129694395672' in .env file

Instead

'client_id' => env('426129694395672'),  

Using env('VarName')是获取名为的环境变量的值VarName in .env file