Codeigniter上传不起作用，服务器错误500

Question

Codeigniter文件上传不起作用。我在其他问题上寻找答案，但我遇到了服务器错误。

<?php
class Upload extends CI_Controller {

  public function __construct() { 
     parent::__construct(); 
     $this->load->helper(array('form', 'url'));
     $this->load->library('upload');
  }

  public function index() { 
     $this->load->view('upload_form', array('error' => ' ' )); 
  } 

  public function do_upload() { 
     $config['upload_path']   = './uploads/'; 
     $config['allowed_types'] = 'gif|jpg|png'; 
     $config['max_size']      = 100; 
     $config['max_width']     = 1024; 
     $config['max_height']    = 768;  
     $this->load->library('upload', $config);
     $this->upload->initialize($config);

     if ( ! $this->upload->do_upload('userfile')) {
        $error = array('error' => $this->upload->display_errors()); 
        $this->load->view('upload_form', $error); 
     }

     else { 
        $data = array('upload_data' => $this->upload->data()); 
        $this->load->view('upload_success', $data); 
     } 
  } 
}

我尝试在上面的代码中使用它，并发生服务器错误500。

$this->upload->initialize($config);

如果我删除了，我只看到了＃34;上传路径似乎无效“。 请帮助。