更新到最新版本后,Codeigniter文件上载不起作用。

将项目文件更新为最新版本的Codeigniter后,当我上载任何文件时,它将返回以下错误:

代码如下:

public function test_upload(){
    $config = array(
        'upload_path'   => './assets/upload_test',
        'allowed_types' => 'gif|jpg|png|jpeg|pdf',
        'max_size'      => '2048',
    );
    if($_FILES['file']['name'] != '')
    {
        $image = 'file';
        $upload_data = $this->do_upload($image, $config);
        if($upload_data['condition']=='error')
        {
            echo json_encode(array('condition'=>'error', 'message'=>$upload_data['error'].' (User image)')); exit;
        }else{
            $profile_picture['file'] = $upload_data['upload_data']['file_name'];
        }
    }
    print_r($profile_picture);exit;
}

public function do_upload($image, $config)
{
    $this->load->library('upload');
    $this->upload->initialize($config);
    if ( ! $this->upload->do_upload($image))
    {
        $error = array('condition'=>'error', 'error' => $this->upload->display_errors());
        return $error;
    }
    else
    {
        $data = array('condition'=>'success', 'upload_data' => $this->upload->data());
        return $data;
    }
}

搜索了很多,但没有找到任何好的解决方案。谢谢大家的回复。