Is it possible to use a Relative path when setting a custom error page in IIS7?

Question

I'm trying to set a custom 404 error page for my web application. The trouble is that this application will be deployed to a number of different environments. Sometimes it will be in a virtual directory and sometimes it won't.

I have the error page in a directory called ErrorPages and have set up my config like this:

   <httpErrors errorMode="Custom" existingResponse="Replace">
     <remove statusCode="404"/>
     <error statusCode="404" path="/VirtualDir/ErrorPages/404.aspx" responseMode="ExecuteURL" />
   </httpErrors>
</system.webServer>

The trouble is when I deploy this to the root of a web site, the /VirtualDir part needs to be removed. If I remove it before deployment then I need to add it back in when deploying to a virtual directory. Is there any way I can set the path to be relative to the virtual directory and not to the site?

I have tried using a ~, but that does not work either, like this:

   <httpErrors errorMode="Custom" existingResponse="Replace">
     <remove statusCode="404"/>
     <error statusCode="404" path="~/ErrorPages/404.aspx" responseMode="ExecuteURL" />
   </httpErrors>
</system.webServer>

Answer 1

You could use web.config transforms to set the path per environment:

web.config

<httpErrors errorMode="Custom" existingResponse="Replace">
  <remove statusCode="404"/>
  <error statusCode="404" path="/VirtualDir/ErrorPages/404.aspx" responseMode="ExecuteURL" />
</httpErrors>

web.Release.config

<httpErrors>
  <error statusCode="404" path="/ErrorPages/404.aspx" responseMode="ExecuteURL" />
</httpErrors>