swfupload 上传遇到404错误

debug日志看不出来啥, 监控也监控不到, 查到配置config如下: 主要是给一个Path地址:

<?xml version="1.0"?>
<configuration>
  <appSettings/>
  <connectionStrings/>
  <system.web>
    <compilation debug="true"/>
    <authentication mode="None"/>
    <customErrors mode="Off"/>
  </system.web>
  <location path="upload.aspx">
    <system.web>
      <httpRuntime maxRequestLength="102400" executionTimeout="3600" />
    </system.web>
  </location>
  <system.webServer>
    <security>
      <requestFiltering>
        <requestLimits maxAllowedContentLength="100000000" />
      </requestFiltering>
    </security>
  </system.webServer>
</configuration>