今天在DEDE后台登陆时出现了问题，导致后台变成空白，再回头登陆时，登陆页面也是一片空白，查看源代码也是一片空白，在网上找了些资料解决了dedecms后台打开空白的解决方法：
找到:include/common.inc.php文件，打开，查找程序代码：
//error_reporting(E_ALL);
error_reporting(E_ALL || ~E_NOTICE);
替换为:
error_reporting(E_ALL);
//error_reporting(E_ALL || ~E_NOTICE);
这一步很重要，因为它会告诉你为什么变成空白的提示信息，保存之后再次进入管理后台,这个时候会发现后台会有错误提示了，根据错误提示来解决问题。
原文提示是:
Warning: Cannot modify header information - headers already sent by (output started at D:\wwwroot\cwled\wwwroot\include\common.inc.php:1) in D:\wwwroot\junxiaowang\wwwroot\include\common.inc.php on line 290
Notice: A session had already been started - ignoring session_start() in D:\wwwroot\junxiaowang\wwwroot\include\userlogin.class.php on line 11
Warning: Cannot modify header information - headers already sent by (output started at D:\wwwroot\cwled\wwwroot\include\common.inc.php:1) in D:\wwwroot\junxiaowang\wwwroot\cwled@guanli\config.php on line 14
Warning: Cannot modify header information - headers already sent by (output started at D:\wwwroot\cwled\wwwroot\include\common.inc.php:1) in D:\wwwroot\junxiaownag\wwwroot\cwled@guanli\config.php on line 37
Notice: A session had already been started - ignoring session_start() in 的解决方法：
在php.ini文件中查找session.auto_start ，将其值设为0：
session.auto_start = 0
Warning: Cannot modify header information - headers already sent by (output started at 的解决方法：
在php.ini文件中查找output_buffering = Off 把 Off修改成On
重启Iis，根据以上错误把dedecms后台打开空白完美解决。
