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I have a ASP.NET 5 site that I want to add custom error pages to. I'm used to adding entries in the web.config (from ASP.NET 4 days) but I want to use the new approach in ASP.NET 5. So I have the following in my Startup.cs class:

if (env.IsEnvironment("Development"))
{
    app.UseErrorPage(ErrorPageOptions.ShowAll);
}
else
{
    app.UseStatusCodePagesWithReExecute("/Home/Error");
    app.UseErrorHandler("/Home/Error");
}

When I run locally using kestral my error page is displayed properly. However, when I deploy to Azure I get the very generic white error page when I try to test 404 errors:

"The resource you are looking for has been removed, had its name changed, or is temporarily unavailable."

I tried implementing this answer in my web.config and it does not resolve my issue:

https://stackoverflow.com/a/29539669/8320

This is the relevant part of my web.config:

<system.web>
    <customErrors mode="Off" />
</system.web>

I have also ensured that ASPNET_ENV="Production" in the Configure / App Settings section of the Azure Website.

Any ideas? If I can provide more info let me know.

Community
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Mike
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    StatusCodePages middleware and 404 responses seem to behave differently on IIS. You can take a look at this issue to see if that work around fixes your issue: https://github.com/aspnet/Diagnostics/issues/144 – Kiran Jun 17 '15 at 21:13
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    Thank you @KiranChalla that seemed to resolve the issue. I do have a question about why I'm getting a blank/empty window when I leave the env.IsEnvironment("Development") block in place. I only get the proper error screens to display when I remove the if statement and the app.UserErrorPage(ErrorPageOptions.ShowAll); Any ideas? Also, if you make your comment an answer I'll up-vote it. – Mike Jun 18 '15 at 22:03

1 Answers1

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IIS is a tricky beast and we're still working through this in ASP.NET 5. When you run on IIS, we run through the middleware pipeline and then call back into IIS native modules if nothing handled the request. When you get a 404 that was un-handled by any middleware, it will re-enter the IIS pipeline and trigger IIS specific error pages. The UseStatusCodePagesWithReExecute middleware still runs, but by then, IIS has already sent the headers and body to the client (browser in this case).

davidfowl
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