<system.web>

    <compilation debug="true" targetFramework="4.0" />

    <httpRuntime maxRequestLength="" executionTimeout=""></httpRuntime>

</system.web>

<system.webServer>

    <security>

      <requestFiltering>

        <!--这个节点直接决定了客户端文件上传最大值-->

        <requestLimits maxAllowedContentLength="" />

      </requestFiltering>

    </security>

  </system.webServer>