Application is running inside IIS process but is not configured to use IIS server .NET Core 3.0

Question

I have migrated our application from .NET Core 2.2 to version 3.0. Actually I created the new application in 3.0 from scratch and then copied source code files. Everything looks great but when I try to run the application within Visual Studio 2019 I get the exception:

Application is running inside IIS process but is not configured to use IIS server

Here is my Program.cs

public static class Program
{
    public static void Main(string[] args)
    {
        CreateHostBuilder(args).Build().Run();
    }

    public static IHostBuilder CreateHostBuilder(string[] args) =>
        Host.CreateDefaultBuilder(args)
            .ConfigureWebHostDefaults(webBuilder =>
            {
                webBuilder.UseContentRoot(Directory.GetCurrentDirectory());
                webBuilder.UseKestrel();
                webBuilder.UseIISIntegration();
                webBuilder.UseStartup<Startup>();
            });
}

The error occurs at the line: CreateHostBuilder(args).Build().Run(); It worked fine in .NET Core 2.2 but it doesn't want to run as 3.0. I cannot find anything else that should be done. Something new in the Startup.cs? I don't know.

Remove `.UseKestrel()`. The migration process is documented, in [Migrate from ASP.NET Core 2.2 to 3.0](https://learn.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.0&tabs=visual-studio). 3.0 is a major version with expected (and documented) breaking changes. The default hosting model now is [in-process activation](https://learn.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.0&tabs=visual-studio#in-process-hosting-model) — Panagiotis Kanavos, Sep 24 '19 at 14:59

score 127 · Accepted Answer · edited Mar 24 '20 at 06:46

127

I also came across this issue while following the documentation https://learn.microsoft.com/en-us/aspnet/core/migration/22-to-30?view=aspnetcore-3.0&tabs=visual-studio

For your case I have checked and the code below will work, with the call to webBuilder.UseKestrel() removed.

public static IHostBuilder CreateHostBuilder(string[] args) =>
       Host.CreateDefaultBuilder(args)
           .ConfigureWebHostDefaults(webBuilder =>
           {
               webBuilder.UseContentRoot(Directory.GetCurrentDirectory());
               webBuilder.UseIISIntegration();
               webBuilder.UseStartup<Startup>();
           });

edited Mar 24 '20 at 06:46

peregrination

2,460
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answered Sep 25 '19 at 06:14

Satyajit

2,150
2
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19

Yes, leaving out UseKestrel() did the job. Thanks a lot! – Ondrej Vencovsky Sep 25 '19 at 12:12
20

BTW, it works, because `ConfigureWebHostDefaults` does both: `UseKestrel` and `UseIIS` internally. Those methods bind `IServer` to Kestrel or IIS. ServiceProvider works in "last wins" manner. So, if you write `UseKestrel` - it's last, if you leave it out `UseIIS` is last. – Roman Tymchyshyn Oct 24 '19 at 12:58
4

Also, `UseIISIntegration` is also called inside `ConfigureWebHostDefaults`. – Roman Tymchyshyn Oct 24 '19 at 12:59
4

Is it possible to create a "binary" that is compatible to both, IIS and Kestrel? It would be a pity, to create different deployments, just because of these two lines of code... – Nicolas Oct 08 '21 at 11:43
This answer works on my end. Thank you! – Marc Kenneth Lomio Oct 19 '21 at 08:01
is there anything that would work for all servers? this is not working on my end – aj go Sep 22 '22 at 11:47
also I'm trying to remove server header which is available only in useKestrel middleware – aj go Sep 22 '22 at 11:47

score 40 · Answer 2 · answered Aug 20 '20 at 13:11

I had the same error then to fix my problem I needed to change webBuilder.UseKestrel(); to ConfigureKestrel(serverOptions => {})

My Program.cs before:

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.UseKestrel();
            webBuilder.UseStartup<Startup>();
        });

My Program.cs fixed:

public static IHostBuilder CreateHostBuilder(string[] args) =>
    Host.CreateDefaultBuilder(args)
        .ConfigureWebHostDefaults(webBuilder =>
        {
            webBuilder.ConfigureKestrel(serverOptions =>
            {
            })
            .UseStartup<Startup>();
        });

score 26 · Answer 3 · answered Feb 28 '20 at 08:52

26

In my case I ran wrong profile (IIS Express) in Visual Studio by carelessness.

answered Feb 28 '20 at 08:52

flam3

1,897
2
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score 8 · Answer 4 · answered Mar 29 '21 at 08:21

As @flam3 suggested, you need to select a profile with correct command.

Open Solution Explorer -> Your Project Name -> Properties -> launchSettings.json file.

The value of the key commandName should be 'Project' instead of 'IIS Express'

So select profile with the name Elsa.Samples.UserRegistration.Web(in my case). See below. Or you may try changing IISExpress to Project on line no 19

score 6 · Answer 5 · answered Feb 14 '22 at 17:10

6

For Visual Studio 2019 and 2022

Go to API project properties: Debug Tab -> General -> Hit "Open Debug launch profiles UI"

Scroll Down to Hosting Model and Select "Out Of process"

Then, you will be able to run your application with no Issues.

answered Feb 14 '22 at 17:10

David Castro

1,773
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Application is running inside IIS process but is not configured to use IIS server .NET Core 3.0

5 Answers5

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