问题描述：

Server Error in ‘/‘ Application.
Runtime Error
Description: An application error occurred on the server. The current custom error settings for this application prevent the details of the application error from being viewed remotely (for security reasons). It could, however, be viewed by browsers running on the local server machine. 

Details: To enable the details of this specific error message to be viewable on remote machines, please create a <customErrors> tag within a "web.config" configuration file located in the root directory of the current web application. This <customErrors> tag should then have its "mode" attribute set to "Off".

<!-- Web.Config Configuration File -->

<configuration>
<system.web>
<customErrors mode="Off"/>
</system.web>
</configuration>

Notes: The current error page you are seeing can be replaced by a custom error page by modifying the "defaultRedirect" attribute of the application‘s <customErrors> configuration tag to point to a custom error page URL.

<!-- Web.Config Configuration File -->

<configuration>
<system.web>
<customErrors mode="RemoteOnly" defaultRedirect="mycustompage.htm"/>
</system.web>
</configuration>

新建站点的时候，经常碰到这个问题，搜索之后就是修改配置文件，但是效果不好，有后遗症。

最终解决方案：

.检查iis—web服务扩展--ASP.NET v2.0.50727和Active Server Pages有没有设置允许
（如果没有服务扩展重新注册IIS服务扩展，在“开始”-“运行”里输入如入命令，回车C:\WINDOWS\Microsoft.NET\Framework\v2.0.50727\aspnet_regiis -i -enable）
2.控制面板--管理工具--服务--asp.netstate service 设置为自动，并启动
1执行后如果不行最好重新建立一个虚拟目录或网站浏览
最近出现应该是更新了.net的补丁造成的

如何解决？ Server Error in '/' Application.