ASP.NET Custom Errors being ignored

Question

I have custom errors configured in my web.config, but IIS 6.0 is returning the custom error specified in the Custom Errors tab of the website configuration.

  <system.web>
        <customErrors>
              <error statusCode="404" redirect="UrlRedirect.aspx" />
        </customErrors>
  </system.web>

What can I be missing?

Answer 1

You might be missing mode="On":

<system.web>
        <customErrors mode="On">
              <error statusCode="404" redirect="UrlRedirect.aspx" />
        </customErrors>
</system.web>

Answer 2

Actually, if I'm understanding your dilemma correctly, it sounds like the custom error IS being returned, if this is not what you want you will need to turn the mode to "Off" or "RemoteOnly" in order to see detailed error messages in your environment.

<customErrors mode="Off"/>

Answer 3

Bear in mind that the 404 handler specified in the web.config only kicks in for files handled by the ASP.NET runtime - .htm, images, css, javascript will all be handled by the 404 page specified in your hosts IIS settings.

If you want these file types to be handled by your custom error, you'll need to set IIS to direct 404's to UrlRedirect.aspx.