IIS7 Overrides customErrors when setting Response.StatusCode?

Nicholas_H_22505 0
Viewed 58763

Having a weird problem here. Everybody knows that if you use web.config's customErrors section to make a custom error page, that you should set your Response.StatusCode to whatever is appropriate. For example, if I make a custom 404 page and name it 404.aspx, I could put <% Response.StatusCode = 404 %> in the contents in order to make it have a true 404 status header.

Follow me so far? Good. Now try to do this on IIS7. I cannot get it to work, period. If Response.StatusCode is set in the custom error page, IIS7 seems to override the custom error page completely, and shows its own status page (if you have one configured.)

Has anyone else seen this behavior and also maybe know how to work around it? It was working under IIS6, so I don't know why things changed.

Note: This is not the same as the issue in ASP.NET Custom 404 Returning 200 OK Instead of 404 Not Found

iis-7 asp.net
7 Answers

Set existingResponse to PassThrough in system.webServer/httpErrors section:

  <system.webServer>
    <httpErrors existingResponse="PassThrough" />
  </system.webServer>

Default value of existingResponse property is Auto:

Auto tells custom error module to do the right thing. Actual error text seen by clients will be affected depending on value of fTrySkipCustomErrors returned in IHttpResponse::GetStatus call. When fTrySkipCustomErrors is set to true, custom error module will let the response pass through but if it is set to false, custom errors module replaces text with its own text.

More information: What to expect from IIS7 custom error module

user_141310

The easiest way to make the behavior consistent is to clear the error and use Response.TrySkipIisCustomErrors and set it to true. This will override the IIS global error page handling from within your page or the global error handler in Application_Error.

Server.ClearError();
Response.TrySkipIisCustomErrors = true;

Typically you should do this in your Application_Error handler that handles all errors that your application error handlers are not catching.

More detailed info can be found in this blog post: http://www.west-wind.com/weblog/posts/745738.aspx

user_111970
Nicholas_H_225050

By default IIS 7 uses detailed custom error messages so I would assume that Response.StatusCode will equal 404.XX rather than just 404.

You can configure IIS7 to use the simpler error message codes or modify your code handling the more detailed error messages that IIS7 offers.

More info available here: http://blogs.iis.net/rakkimk/archive/2008/10/03/iis7-enabling-custom-error-pages.aspx

Further investigation revealed I had it the wrong way around - detailed messages aren't by default but perhaps they've been turned on, on your box if you're seeing the different error messages that you've mentioned.

nullnvoid_434750
Related