(SharePoint 2010)用户代码未处理 FileNotFoundException

Question:在Windows Server 2008 上写代码访问SharePoint 2010 站点集时报错！

Error:The Web application at http://dexter-pc:81/SitePages/Home.aspx could not be found. Verify that you have typed the URL correctly. If the URL should be serving existing content, the system administrator may need to add a new request URL mapping to the intended application.

Solution:由于访问SharePoint 2010的程序集必须是X64位的，所以出现此错误。在Visual Studio 2010中的【配置管理器】->【活动解决方案平台】，新建解决方案平台，如图。