laravel 错误之index.php:使用git上传代码到远端，删除本地代码，再clone代码后一直报500

 最近在我的个人服务器上搭建了个laravel环境，新建了个laravel项目，可以正常运行。代码提交到gitee后删除本地代码，再从仓库拉代码，这时候发现代码跑不了了，一直报500。百度了很多方法：php artisan cache:clear、composer update、composer dumpautoload、php artisan key:generate之后一直没用。

无奈之下，只能一步步调试了：首先检查入口文件index.php,发现问题就在这边：访问public下面的其他目录时都可以正常访问，只有index.php会报500。那么，只有对index.php进行仔细分析才能找到问题所在：

";
/**
 * Laravel - A PHP Framework For Web Artisans
 *
 * @package  Laravel
 * @author   Taylor Otwell 
 */

/*
|--------------------------------------------------------------------------
| Register The Auto Loader
|--------------------------------------------------------------------------
|
| Composer provides a convenient, automatically generated class loader for
| our application. We just need to utilize it! We'll simply require it
| into the script here so that we don't have to worry about manual
| loading any of our classes later on. It feels nice to relax.
|
*/

require __DIR__.'/../bootstrap/autoload.php';
echo "过了一会"."
";
/*
|--------------------------------------------------------------------------
| Turn On The Lights
|--------------------------------------------------------------------------
|
| We need to illuminate PHP development, so let us turn on the lights.
| This bootstraps the framework and gets it ready for use, then it
| will load up this application so that we can run it and send
| the responses back to the browser and delight our users.
|
*/

$app = require_once __DIR__.'/../bootstrap/app.php';
echo "又过了一会"."
";
/*
|--------------------------------------------------------------------------
| Run The Application
|--------------------------------------------------------------------------
|
| Once we have the application, we can handle the incoming request
| through the kernel, and send the associated response back to
| the client's browser allowing them to enjoy the creative
| and wonderful application we have prepared for them.
|
*/

$kernel = $app->make(Illuminate\Contracts\Http\Kernel::class);
echo "kernel正常"."
";
$response = $kernel->handle(
    $request = Illuminate\Http\Request::capture()
);
echo "response正常"."
";
$response->send();

$kernel->terminate($request, $response);

 这样就发现代码停在了”kernel正常“这边。

于是，现在的主要问题就是"Illuminate\Http\Request::capture()"这个方法为什么会失败了。

仔细分析一下代码上传前后的区别，突然想起来git有一个   .gitignore 文件会在代码提交的时候过滤掉一些文件，其中默认会有vender文件夹，但这个文件夹对项目的启动没有太大影响，于是转移目光，那么还会变的就只有  .env文件了，打开项目一看，居然发现没有  .env 文件。 原来如此，真正的原因是没有 .env,大家都知道项目启动是需要app_key的，而app_key会保存在  .env 文件中，这在项目部署时是一个重点，因为要将一些隐私去掉，所以那时候 .env文件会被默认忽略。

问题解决！