将文件从一台服务器传输到另一台服务器时出现问题

大家好，我在使用 php 将文件从服务器上传到我的朋友服务器时遇到问题。起初我收到一个 26 错误，现在我收到此错误：

Error: Possible file upload attack: filename ''.Array ( ) 1

下面是我的代码

<?php
 $ch = curl_init();
chmod("grademegood.us/uploadedfiles/hello.txt", 0755);
  $post =array(
  'file' => '@' . realpath('./uploadedfiles/hello.txt')
 );
 curl_setopt($ch, CURLOPT_POSTFIELDS,$post);
 curl_setopt($ch, CURLOPT_URL, "http://friendsdomain.com/upload.php");
 curl_setopt($ch, CURLOPT_POST,true);
 $data = curl_exec($ch);
 if (curl_errno($ch))
{
 print curl_errno($ch);
}
else
{
  curl_close($ch);
 }
 echo $data;
 ?>

这是接收方代码：

<?php
$uploads_dir = './phpbackend/';
if(is_uploaded_file($_FILES['userfile']['tmp_name'])) 
{
  echo  "File ".  $_FILES['userfile']['name']  ." uploaded successfully to
 $uploads_dir/$dest.'n";
 $dest=  $_FILES['userfile'] ['name'];
 move_uploaded_file ($_FILES['userfile'] ['tmp_name'], "$uploads_dir/$dest");
} 
 else 
  {
    echo "Possible file upload attack: ";
    echo "filename '". $_FILES['userfile']['tmp_name'] . "'.";
    print_r($_FILES);
  }
?>

请我需要一些帮助。