ASP.NET Core 404 Error on IIS 10

Question

I have a problem with ASP.NET Core web application running on IIS 10. I am developing a Single Page Application with AngularJS.

The index.html loads perfectly but the backend requests are failing with 404 error code on the IIS 10. From Visual Studio with IIS Express it works perfectly.

Can anyone spot how can I fix the backend requests?

Here's my Program.cs

public static void Main(string[] args)
{
    var host = new WebHostBuilder()
        .UseKestrel()
        .UseContentRoot(Directory.GetCurrentDirectory())
        .UseIISIntegration()
        .UseStartup<Startup>()
        .Build();

    host.Run();
}

And here's my Configure method from Startup.cs

public void Configure(IApplicationBuilder app, IHostingEnvironment env, ILoggerFactory loggerFactory)
{
    app.UseDefaultFiles();

    app.UseStaticFiles();

    app.UseIdentity();

    // Custom middleware for Angular UI-Router
    app.Use(async (context, next) =>
    {
        if (!Path.HasExtension(context.Request.Path.Value)
        && context.Request.HttpContext.Request.Headers["X-Requested-With"] != "XMLHttpRequest"
        && context.Request.Method.ToUpper() != "POST"
        && context.Request.Method.ToUpper() != "PUT"
        && context.Request.Method.ToUpper() != "DELETE")
        {
            await context.Response.WriteAsync(File.ReadAllText(env.WebRootPath + "/index.html"));
        }

        await next();
    });

    app.UseMvc(routes =>
    {
        routes.MapRoute(
            name: "default",
            template: "api/{controller=Home}/{action=Index}/{id?}");
    });
}

Enable ASP.NET Core logging (probably with a Debug log level) and see if there are any messages as to why this is failing — Kiran, Jul 22 '16 at 21:54

score 33 · Answer 1 · answered Jun 23 '17 at 09:44

33

In my case the problem was that my controller threw an exception, thus the framework tried to use the exception handler page which was no available, thus the 404 error, the controller itself was throwing 500 error

answered Jun 23 '17 at 09:44

mohas

1,911
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8

How did you troubleshoot – Hristo Alexsiev May 25 '20 at 09:07
2

Yeah, I would be interested to know too. In the development mode the exception should be showing on the page, but it isn't. Not sure if there is an exception that is causing my 404 or not – Mocas May 26 '20 at 11:55
2

I think the routing is broken for some reason, I can get to the paga if I include the full path,... This will work -> https://localhost:5001/home/index.... This won't work -> https://localhost:5001/home neither this https://localhost:5001/ – Mocas May 26 '20 at 15:49
for check this answer add try catch statement in you controller – Akbar Asghari Nov 06 '20 at 17:58

score 32 · Answer 2 · answered Sep 13 '18 at 13:39

For the benefit of searchers.

I was getting a 404 when Using IIS. I had followed the correct procedure for publishing (here) and deployment as detailed here.

It took some time to figure out, but I eventually found the answer hidden in a Rick Strahl blog post.

Basically, when making the application pool, as well as setting it to 'No Managed Code', I also needed to go into the advanced settings and set the Application Pool Identity to 'Network Service'. It was fine under ApplicationPoolIdentity on my machine, but not on a machine I deployed to.

So, for clarity, my full procedure was:

To create package:

Create dotnet core website (I used Visual Studio 2017)
Publish. Could have used VS's publish function, but I used CLR via the package manager. The command was:

dotnet publish -c Release -r win-x64 --self-contained

I had to use the win-x64 identifier as we have to be compatible with 64-bit Windows Server 2008.

To deploy:

Make a folder in C:\inetpub\wwwroot (e.g. 'testsite')
Take the contents of the publish folder ({root}\bin\Release\netcoreapp2.1\win-x64\publish) and copy it to the new 'testsite' folder (or your equivalent).
Install the dotnet core runtime (not SDK!) on the host machine.
Open IIS. Right click 'Application pools', then 'Add Application Pool'. Create one with the .NET CLR Version set to 'No Managed Code'.
(my machine didn't need this step, but server did).Click on Application pools again. Right click your new App Pool and Choose 'Advanced Settings'. Change the identity to 'Network Service' (as shown in the picture above).
Back at top level IIS, Expand 'Default Web Site', right click the folder of your website and choose 'Convert to application'. Choose your new App Pool with No Managed Code.
Open command prompt as admin and iisreset . You should only need this the first time after you've installed the dotnet core runtime.
Visit the site (e.g. http://localhost/testsite)

According to the MSDN docs you don't need to install the runtime when it's *self contained*: https://learn.microsoft.com/en-us/dotnet/core/deploying/ — Aage, May 20 '20 at 12:23
@Aage - that's a good point - you wouldn't need it for self contained. You will of course still need the .NET Core IIS Hosting Bundle — JsAndDotNet, May 20 '20 at 13:25

score 24 · Accepted Answer · answered Jul 23 '16 at 00:23

24

You code is working on my machine with Kestrel. A good troubleshooting step is to find out whether the problem is with your ASP.NET Core application or with your IIS Hosting configuration.

Try this from the root of your project.

dotnet restore
dotnet run

You will see something like this:

Hosting environment: Production
Content root path: C:\MyApplicationPath
Now listening on: http://localhost:5000
Application started. Press Ctrl+C to shut down.

In your browser go to the following two URLs. If they don't work, then something is wrong with your application. If they do work, something is wrong with your IIS hosting.

localhost:5000        // you will see your index.html page
localhost:5000/api    // you will see your default routes output

answered Jul 23 '16 at 00:23

Shaun Luttin

133,272
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2

Thanks I could fix it. The problem was with my application but it is a little bit weird thing to throw a 404 error if something wrong with the application. – Mate Zabo Jul 23 '16 at 15:06
1

What was wrong with the application? What did your fix involve? – Shaun Luttin Jul 23 '16 at 21:50
1

The problem was a missing configuration file. I have 3 environment appsettings file for Development, Staging and Production with the necessary connection strings. The default publish option contains only the appsettings.json. So I need to change the value to appsettings*.json to copy all of the environment settings. – Mate Zabo Jul 24 '16 at 18:38
Very useful. My API is actually working through IIS and through running the EXE on the server. It seems it's my Swagger page that is giving me the 404. – Christopher Painter Jul 20 '21 at 16:16
Mentioning Swagger gave me an idea, I was receiving 404 accessing http://example.com/mysitepoolname, it turns out I just need to access the correct URL at http://example.com/swagger/index.html and voila, works just fine. (hope to save someone from wasting time digging for a solution) – mirageservo Jul 29 '21 at 06:04

score 7 · Answer 4 · answered Sep 09 '22 at 18:52

in my case, the problem was fixed by setting environment variable in the web.config

<aspNetCore processPath="dotnet"
      arguments=".\MyApp.dll"
      stdoutLogEnabled="false"
      stdoutLogFile=".\logs\stdout"
      hostingModel="inprocess">
  <environmentVariables>
    <environmentVariable name="ASPNETCORE_ENVIRONMENT" value="Development" />
     </environmentVariables>
</aspNetCore>

score 4 · Answer 5 · edited Jun 26 '23 at 00:31

4

I was missing a key file - web.config which IIS needs in order to run your web application. I used the web.config configurations specified here:

https://learn.microsoft.com/en-us/aspnet/core/host-and-deploy/iis/web-config?view=aspnetcore-5.0

Specifically, the configurations for ASP.NET Core Module.

edited Jun 26 '23 at 00:31

desertnaut

57,590
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answered Jul 16 '21 at 14:00

Reboot_87

499
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score 1 · Answer 6 · answered Jul 08 '19 at 07:18

1

Another very silly but probable variant is that the app was deployed in folder different from what you were expecting (ex: your server root instead of sub-folder) due to erroneous deploy settings.

answered Jul 08 '19 at 07:18

Nick Kovalsky

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score 1 · Answer 7 · answered May 30 '20 at 13:35

Had the same issue now which brought me to this page. In case anyone is having this issue now this was what fixed it for me:

Downloaded and installed dotnet-hosting-3.1.4-win from https://dotnet.microsoft.com/download/dotnet-core/thank-you/runtime-aspnetcore-3.1.4-windows-hosting-bundle-installer
Downloaded and installed dotnet-sdk-2.2.207-win-x64 from https://dotnet.microsoft.com/download/dotnet-core/2.2

abovetempo · Answer 8 · 2023-07-05T17:40:52.300

1

If you are using an api call make sure your class has:

[Route("api/[controller]")]
    [ApiController]

above where the class is instantiated.

Also make sure you have:

[HttpGet()]

for example above the api method you are trying to debug.

edited Jul 05 '23 at 17:40

answered Jul 20 '20 at 02:52

abovetempo

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score 1 · Answer 9 · answered Jan 10 '23 at 18:31

I had configured a root directory using .AddRazorPageOptions(rpo => rpo.RootDirectory = "/Folder"), but I forgot and my .cshtml files were still in the root of the project instead. I just had to make the /Folder folder and put my files in there and it worked.

score 1 · Answer 10 · answered May 01 '23 at 19:01

For anyone here with the same issue, it may not be an issue with your deployment. If you are deploying the default sample web api project (WeatherForecastAPI) and then received 404, it is because swagger is not enabled in production or release mode. So there are no controller method to handle the to receive the requests sent to root url.

However if you call the endpoint directly (in this case {your_app_url}/WeatherForecast) then it will work.

score 0 · Answer 11 · answered Oct 18 '20 at 16:25

0

For me the issue was an ISAPI Filter called UrlScan. I had to delete it from the application, only then did it work.

answered Oct 18 '20 at 16:25

frezq

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score 0 · Answer 12 · answered Jan 30 '23 at 19:52

I was missing a handler mapping for AspNetCoreModuleV2.

Request Path: * Module: AspNetCoreModuleV2 Executable: blank Name: aspNetCore (this I believe can be anything you want)

Under Request Restrictions, I unchecked the "Invoke handler only if request is mapped to:" checkbox. Selected All verbs, and Script access.

ASP.NET Core 404 Error on IIS 10

12 Answers12

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