如何引用 “用户控件”在web.config中

<system.web>

    <pages>
      <controls>
        <add tagPrefix="user" tagName="RandomQuote" src="~/UserControls/RandomQuote.ascx"/>
      </controls>
    </pages>

  </system.web>

但是：
Be aware that there is one important limitation when registering User Controls in the Web.config file. When a User Control is registered in the Web.config file, you cannot place the User Control in the same folder as a page that uses the User Control. To work around this limitation, you should always place all of your User Controls in a separate folder. I typically create a User Controls folder for each of my web applications.