老外真多废话
其实在INTERNET选项里把显示友好错误信息勾掉酒可以了

Why do I get a 500 Internal Server error for all ASP errors?     (2,943 requests)
If you're using IE5 and/or developing on Windows 2000, you might find it difficult to debug ASP errors in a browser. This is because IE5 has a ridiculous default option that suppresses errors to a more "friendly" error (which, IMHO, is a lot more cryptic than what they'd get otherwise).

To circumvent this silliness and get real ASP errors, go to IE's Tools/Internet Options menu, and on the advanced tab, uncheck "Show friendly HTTP error messages."

After you've disabled this default setting, refresh the page in question. There are three possible outcomes: (1) the page will magically work again; (2) the page will give you a more detailed error (e.g. Stack Overflow or Syntax Error), including a line number; or (3) you will get "Server Application Error" - which means that at some point IIS got confused about the current application.

If (3) is what happens, you can remedy this simply by going into Internet Services Manager. Right-click the application in question (or Default Web Site, if an application is not relevant), select properties, hit the "Home Directory" tab, click the "Remove" button, and then click the "Create" button. Follow with Apply/OK etc and get out of Internet Services Manager. Refresh your page, and all should be well again.

If you are still getting errors like 'page not found' then go into Internet Services Manager, right-click Default Web Site, choose Properties, and on the Home Directory tab, click the Configuration button. On the App Debugging tab, make sure "Send detailed ASP error messages to client" is selected.