Notice: A session had already been started – ignoring session_start()...
出现以下错误的解决办法：
Notice: A session had already been started – ignoring session_start() in .. on line ..
之所以出现这种情况是页面中多次使用了 session_start()函数

有以下两种解决办法：
1) in php.ini file set session.autostart to 0 配置php.ini 设置session.autostart =0
session.auto_start = 0

2) In your code use this line 在出现错误的页面中编辑你的代码如下：
if (!session_id()) session_start();
instead of
session_start();