title: How to use FileUpload in UpdatePanel?
body: <p>I know that such question was has been many times already but I couldn't find any right solution for my problem.</p>
  
  <p>I have MasterPage1 with ScriptManager. There is MasterPage2 in it. In 2-nd MasterPage I placed Control with UpdatePanel. In this UP I placed FileUpload and SubmitButton:</p>
  
  <p>Master1(with SM) &lt;= Master2 &lt;= Control(with FU and But)</p>
  
  <p>I tried to debug method But_OnClick and saw that FU.PostedFile == null.</p>
  
  <p>I tried to place PostBackTrigger to But in UP, I tried to do it from Control's code behind using something like Page.Master.Master.FindControl("ScriptManager") and it doesn't work.</p>
  
  <p>And I even tried to use AjaxControlToolkit...</p>