Laravel 用户''@'localhost'对数据库'forge'的访问被拒绝随机出现

我有一个数据库搜索功能，但有时我会收到以下消息:

[2016-02-04 07:03:18] local.ERROR: PDOException: SQLSTATE[HY000] [1044] Access denied for user ''@'localhost' to database 'forge' in C:\xampp\htdocs\reko\api\vendor\laravel\framework\src\Illuminate\Database\Connectors\Connector.php:55
Stack trace:
#0 C:\xampp\htdocs\reko\api\vendor\laravel\framework\src\Illuminate\Database\Connectors\Connector.php(55): PDO->__construct('mysql:host=loca...', 'forge', '', Array)
...

在十次通话中，有一次我收到了500条错误信息，但我不知道为什么.其他电话给出了正确的结果.

埃文先生

APP_ENV=local
APP_DEBUG=true
APP_KEY=bJM6O0MnrIPaTNwKKOqNJkGinRDv1fnc

DB_HOST=localhost
DB_DATABASE=reko
DB_USERNAME=root
DB_PASSWORD=

CACHE_DRIVER=file
SESSION_DRIVER=file
QUEUE_DRIVER=sync

搜索功能:

public function search(Modul $modul, Request $request)
{
    $question = Question::whereModulId($modul->id)
        ->where('value', 'LIKE', '%' . $request->get('keywords') . '%')
        ->with('tags')
        ->whereHas('exams', function ($query) use ($request) {
            $query->where('date', '>=', $request->get('year').'-01-01');
        });
    if (!$request->get('parent'))
        $question->where('type', '<>', 'parent');
    if (!$request->get('own'))
        $question->where('type', '<>', 'own');
    if (!$request->get('normal'))
        $question->where('type', '<>', 'normal');
    if ($request->get('answered'))
        $question->has('answers');
    return $question->paginate(10);
}

数据库php

'mysql' => [
        'driver'    => 'mysql',
        'host'      => env('DB_HOST', 'localhost'),
        'database'  => env('DB_DATABASE', 'forge'),
        'username'  => env('DB_USERNAME', 'forge'),
        'password'  => env('DB_PASSWORD', ''),
        'charset'   => 'utf8',
        'collation' => 'utf8_unicode_ci',
        'prefix'    => '',
        'strict'    => false,
    ],

I haven't modified the 数据库php file and all other calls work great.