Core: System.InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request

[AhmedMKamal]

I got this error when I tried to run a released app

Command used to publish dotnet publish --configuration Release

Result:

Hosting environment: Production
Content root path: /path-to-my-app/publish
Now listening on: http://localhost:5000
Now listening on: https://localhost:5001
Application started. Press Ctrl+C to shut down.
fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[1]
      An unhandled exception has occurred while executing the request.
System.InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request.
Your application is running in Production mode, so make sure it has been published, or that you have built your SPA manually. Alternatively you may wish to switch to the Development environment.

   at Microsoft.AspNetCore.SpaServices.SpaDefaultPageMiddleware.<>c__DisplayClass0_0.<Attach>b__1(HttpContext context, Func`1 next)
   at Microsoft.AspNetCore.Builder.UseExtensions.<>c__DisplayClass0_1.<Use>b__1(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
fail: Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware[3]
      An exception was thrown attempting to execute the error handler.
System.InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request.
Your application is running in Production mode, so make sure it has been published, or that you have built your SPA manually. Alternatively you may wish to switch to the Development environment.

   at Microsoft.AspNetCore.SpaServices.SpaDefaultPageMiddleware.<>c__DisplayClass0_0.<Attach>b__1(HttpContext context, Func`1 next)
   at Microsoft.AspNetCore.Builder.UseExtensions.<>c__DisplayClass0_1.<Use>b__1(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
fail: Microsoft.AspNetCore.Server.Kestrel[13]
      Connection id "0HLFDGHBE8F9H", Request id "0HLFDGHBE8F9H:00000001": An unhandled exception was thrown by the application.
System.InvalidOperationException: The SPA default page middleware could not return the default page '/index.html' because it was not found, and no other middleware handled the request.
Your application is running in Production mode, so make sure it has been published, or that you have built your SPA manually. Alternatively you may wish to switch to the Development environment.

   at Microsoft.AspNetCore.SpaServices.SpaDefaultPageMiddleware.<>c__DisplayClass0_0.<Attach>b__1(HttpContext context, Func`1 next)
   at Microsoft.AspNetCore.Builder.UseExtensions.<>c__DisplayClass0_1.<Use>b__1(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.Builder.RouterMiddleware.Invoke(HttpContext httpContext)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.StaticFiles.StaticFileMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Diagnostics.ExceptionHandlerMiddleware.Invoke(HttpContext context)
   at Microsoft.AspNetCore.Server.Kestrel.Core.Internal.Http.HttpProtocol.ProcessRequests[TContext](IHttpApplication`1 application)

dotnet version 2.1.302
OS Ubuntu 18.04 LTS

[AhmedMKamal]

Ok, it was about coping the ClientApp file please close this issue.

[DwiYI]

hi i get same problem, how to solve this issue ?
are you copying ClientApp source file or after build ?

[abdu292]

@AhmedMKamal Hi, how did you solve this? I have the same issue after publishing the app on to the server.

[AhmedMKamal]

@DwiYI @abdu292 check outputPath at angular.json and spa.Options.SourcePath at Startup class.

Example:

// angular.json
...
"outputPath": "dist"

// Startup.cs
...
spa.Options.SourcePath = "ClientApp"

my problem was that when i run the build command the Angular app moved to ClientApp/dist/dist instead of ClientApp/dist

[DwiYI]

i have solved the issue. I am using kestrel to serve content from asp .net core.
my issue is write wrong path (working directory) in kestrel service.

[Service]
WorkingDirectory=/var/www/helloapp
ExecStart=/usr/bin/dotnet /var/www/helloapp/helloapp.dll

[abdu292]

Thanks a lot @AhmedMKamal & @DwiYI

[ColinM9991-zz]

@DwiYI

I am also using systemd to host my ASP.NET Core + Angular app on Linux and have this issue.

Can you please confirm whether your index.html lives in the specified working directory? I'm quite unsure as to what's causing this issue as everything is configured as it should and the application does work just fine in production, but my logs are riddled with this error.

[DwiYI]

@ColinM9991

my _index.html_ is inside dist folder. and make sure spa.Options.SourcePath = "ClientApp"

this is my folder structure (inside /var/www/helloapp)

-ClientApp/dist/index.html
-ClientApp/dist/main.js
-wwwroot/favicon.ico
-helloapp.dll
-appsettings.json
-etc

[ColinM9991-zz]

@DwiYI

Thank you for confirming your structure.

The source path in the Startup.cs and angular.json files is correct for me, the application builds and runs successfully but my logs are plagued with this error regardless, I'm wondering if it's a Linux file path issue as I host on Ubuntu 18.04 with nginx as a reverse proxy as described here https://docs.microsoft.com/en-us/aspnet/core/host-and-deploy/linux-nginx?view=aspnetcore-2.2#configure-a-reverse-proxy-server

[HalidCisse]

Solved it by adding :
new WebHostBuilder() .UseContentRoot(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location))

[kakins]

My issue was with setting a custom ASPNETCORE_ENVIRONMENT variable in launchSettings.json. This was on a new project, and I had forgotten to modify the following line in the Startup.cs Configure() method.

From

if (env.IsDevelopment())

To

if (Environment.IsEnvironment("MyCustomEnv"))

Because this if block wasn't being executed, the spa.UseAngularCliServer method was not being called while debugging.

[eltiare]

I'm getting this error randomly. It works most of the time.

[liberalmeida]

Solved it by adding :
new WebHostBuilder() .UseContentRoot(Path.GetDirectoryName(Assembly.GetExecutingAssembly().Location))

Where did you add this?

[liberalmeida]

WorkingDirectory

@DwiYI Where did you add this?

[eltiare]

@liberalmeida WebHostBuilder is usually found in Program.cs - the entrypoint.