遇到PHP错误严重性：警告消息：mkdir（）：权限被拒绝

Question

A PHP Error was encountered
Severity: Warning

Message: mkdir(): Permission denied

Filename: drivers/Session_files_driver.php

Line Number: 136

Backtrace:

File: /home/worldwhe/public_html/index.php
Line: 315
Function: require_once

我该如何解决？