httpErrors shows 500 error instead of YSOD on local machine

Question

I am using httpErrors in my sites web.config to handle 404 errors. This was not working correctly until I added existingResponse="Replace" to the node but now I dont get any yellow screen of death errors on my local development machine.

<httpErrors errorMode="Custom" existingResponse="Replace" >
      <remove statusCode="404" subStatusCode="-1" />
      <error statusCode="404" prefixLanguageFilePath="" path="/error.aspx?c=404" responseMode="ExecuteURL" />
 </httpErrors>

Answer 1

Try changing the existingResponse value to Auto. That worked for me. I'm now able to use a custom 404 page, while also seeing the yellow screen of death errors.