Server Application Unavailable
The web application you are attempting to access on this web server is currently unavailable. Please hit the "Refresh" button in your web browser to retry your request.
Administrator Note: An error message detailing the cause of this specific request failure can be found in the application event log of the web server. Please review this log entry to discover what caused this error to occur.
第一次出现这个问题，重新建了个项目2.0的。把web.config拷贝过去就好了。
第二次这样也不行了。
打开IIS属性，应用程序池选MSSharePointAppPool又对了。
