ASP报错：Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the

VS2005中使用AJAX报错提示为：
Sys.WebForms.PageRequestManagerServerErrorException: An unknown error occurred while processing the request on the server. The status code returned from the server was: 404         或 12023

解决方案：

在母版页中引进ScriptManager控件，内容页引入ScriptManagerProxy代理控件，注意母版页中ScriptManager控件作为页面第一个控件。