Laravel：调用未定义的函数App \ Http \ Middleware \ app（）

Question

我的中间件（Laravel 5.8）出现以下错误： 调用未定义的函数App \ Http \ Middleware \ app（）

<?php

namespace App\Http\Middleware;

use Closure;
use Carbon\Carbon;

class ProjectInterval
{
    /**
     * Handle an incoming request.
     *
     * @param  \Illuminate\Http\Request  $request
     * @param  \Closure  $next
     * @return mixed
     */
    public function handle($request, Closure $next)
    {
        $starts = Carbon::parse(config('project.start_date'));
        $expires = Carbon::parse(config('project.end_date'));
        $isDebug = app()->environment('local') || app()->environment('testing');

        if (now()->gte($expires)) {
            return redirect()->route('getDisabled');
        } elseif (now()->lt($starts) && !$isDebug) {
            return redirect()->route('getCountdown');
        }

        return $next($request);
    }
}

令人惊讶的是，这仅在生产服务器上发生，而不在我的本地测试环境上发生。 我已经使用dump-autoload运行composer，但错误仍然存​​在。

Composer.json：

"autoload": {
        "psr-4": {
            "App\\": "app/"
        },
        "classmap": [
            "database/seeds",
            "database/factories"
        ]
    },

HTTP内核类：

/**
     * The application's route middleware.
     *
     * These middleware may be assigned to groups or used individually.
     *
     * @var array
     */
    protected $routeMiddleware = [
        //...
        'dates' => \App\Http\Middleware\ProjectInterval::class,
        //...
    ];

任何帮助将不胜感激。