最近在使用ajax的时候经常出现下面的问题:
Sys.WebForms.PageRequestManagerParserErrorException:The message received from the server
count not be parsed.Common causes for this error are when the response is modified by calls to response.Write(),response filters,HttpModules,or server trace is enabled.
Details:Error parsing near '|<html>
<head>

解决办法：

用微软的ajax框架,弹出提示框应该用:
ScriptManager.RegisterStartupScript(this.UpdatePanel1, this.GetType(), "updateScript", "alert('Your subscription is successful.);", true);