Intermittent ObjectDisposedException in SPA Hosting

[Sayan751]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

I have a small aspnetcore service to host/serve a SPA. Only intermittently, I am getting the following error in the event log.

Category: Microsoft.AspNetCore.Server.HttpSys.HttpSysListener
EventId: 6
SpanId: 9e2d8fa91d335924
TraceId: 9590e80341d42cca7b750ac04d095314
ParentId: 0000000000000000
RequestId: 4000002b-0005-ed00-b63f-84710c7967bb
RequestPath: /app/path/to/a/static/file.ext

ProcessRequestAsync

Exception: 
System.ObjectDisposedException: ObjectDisposed_Generic
ObjectDisposed_ObjectName_Name, Microsoft.AspNetCore.Server.HttpSys.ResponseBody
   at Microsoft.AspNetCore.Server.HttpSys.ResponseBody.CheckDisposed()
   at Microsoft.AspNetCore.Server.HttpSys.ResponseBody.WriteAsync(Byte[] buffer, Int32 offset, Int32 count, CancellationToken cancellationToken)
   at System.IO.Stream.WriteAsync(ReadOnlyMemory`1 buffer, CancellationToken cancellationToken)
   at Microsoft.AspNetCore.Server.HttpSys.ResponseStream.WriteAsync(ReadOnlyMemory`1 buffer, CancellationToken cancellationToken)
   at System.IO.Pipelines.StreamPipeWriter.FlushAsyncInternal(Boolean writeToStream, ReadOnlyMemory`1 data, CancellationToken cancellationToken)
   at System.IO.Pipelines.StreamPipeWriter.CompleteAsync(Exception exception)
   at Microsoft.AspNetCore.Server.HttpSys.RequestContext.CompleteAsync()
   at Microsoft.AspNetCore.Server.HttpSys.RequestContext`1.ExecuteAsync()
   at Microsoft.AspNetCore.Server.HttpSys.RequestContext`1.ExecuteAsync()

However, the app runs in the browser without any issue. This problem is more prominent when running the automated e2e tests (using Playwright).

This is how I am configuring the SPA static files.

public class Startup
{
  public void ConfigureServices(IServiceCollection services)
  {
    services.AddSpaStaticFiles(opt =>
    {
      opt.RootPath = _Configuration.GetValue("Webroot", "./Content");
    });
  }

  public void Configure(IApplicationBuilder app, IWebHostEnvironment env, ILogger<Startup> logger, IConfiguration config)
  {
    app.UseSpaStaticFiles(new StaticFileOptions
    {
      OnPrepareResponse = context =>
      {
        if (context.Context.Response.HasStarted || context.Context.Response.StatusCode != (int)HttpStatusCode.OK) return;
        context.Context.Response.Headers["Cache-Control"] = "public, max-age=1000";
        context.Context.Response.Headers["Vary"] = "Accept-Encoding";
      }
    });
  }
}

Expected Behavior

The superfluous (as there is no error at the client/browser) error log should be avoided.

Steps To Reproduce

No response

Exceptions (if any)

No response

.NET Version

6.0.301

Anything else?

No response

[javiercn]

@Sayan751 thanks for contacting us.

We have changed the way we approach SPAs on 6.0, we recommend publishing the contents to the wwwroot folder and using app.MapFallbackToFile to serve the SPA as a fallback. You can check a freshly created template for reference on how to update it.

Let us know if you experience issues after making the suggested changes.

Hi @Sayan751. We have added the "Needs: Author Feedback" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

[Sayan751]

@javiercn I am serving multiple SPAs from the hosting service. It is done using something like below.

app.MapWhen(
  c => FunctionThaMatchesTheRequestPathWithOneOfTheSPA,
  c => c.UseSpa(spa => {
   // this is from the Microsoft.AspNetCore.SpaServices.Extensions nuget
  })
)

Can you please highlight how the same can be achieved using the MapFallbackToFile or in any parallel in the new API?

Moreover, I tried migrating to the new API, and IMO there aren't many major changes I can use. The following is what I currently have. However, I am still getting the same exception when running the tests.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Linq;
using System.Net;
using System.Net.Http;
using System.Runtime.Versioning;
using System.Text.Json;
using System.Threading.Tasks;
using IntranetRoleWebAppHostingService;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.AspNetCore.Rewrite;
using Microsoft.Extensions.Configuration;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.FileProviders;
using Microsoft.Extensions.Hosting;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Logging.EventLog;

[assembly: SupportedOSPlatform("windows")]

Directory.SetCurrentDirectory(Directory.GetParent(Process.GetCurrentProcess().MainModule.FileName).FullName);

var config = new ConfigurationBuilder()
  .AddCommandLine(args)
  .AddEnvironmentVariables("ENV_VARS")
  .Build();

var builder = WebApplication.CreateBuilder(new WebApplicationOptions
{
  Args = args,
  WebRootPath = config.GetValue("Webroot", "./Content"),
});

var services = builder.Services;
// here we configure logging and some hosted services

var env = builder.Environment;

builder.WebHost
  .UseConfiguration(config)
  .UseHttpSys();

var app = builder.Build();

app
  .UseHsts()
  .Use((context, next) =>
  {
    var host = config.GetValue<string>("HostingPrefix");
    // configure the CSP
    context.Response.Headers.Add(
      "Content-Security-Policy",
      $"default-src 'none'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self'; font-src 'self' data:; connect-src 'self'{(!string.IsNullOrEmpty(host) ? $" {host}:*" : string.Empty)}"
    );

    // For security reasons we disable everything but the GET verb...
    if (string.Equals(context.Request.Method, HttpMethod.Get.Method, StringComparison.OrdinalIgnoreCase)) return next();

    context.Response.StatusCode = (int)HttpStatusCode.MethodNotAllowed;
    return Task.CompletedTask;
  })
  .UseResponseCaching()
  .UseStaticFiles(new StaticFileOptions
  {
    OnPrepareResponse = context =>
    {
      if (context.Context.Response.HasStarted || context.Context.Response.StatusCode != (int)HttpStatusCode.OK) return;
      context.Context.Response.Headers["Cache-Control"] = "public, max-age=1000";
      context.Context.Response.Headers["Vary"] = "Accept-Encoding";
    },
  });

var layoutFile = Path.Combine(env.WebRootPath, "apps.json");
if (File.Exists(layoutFile))
{
  var rootApps = new HashSet<string>();
  var layout = JsonSerializer.Deserialize<ApplicationLayout>(File.ReadAllText(layoutFile));
  foreach (var category in layout.categories)
    foreach (var application in category.apps)
    {

      var parts = application.path.Split(new[] { '/' }, StringSplitOptions.RemoveEmptyEntries);
      if (rootApps.Contains(parts[0])) continue;
      rootApps.Add(parts[0]);
      var physicalPath = parts[0];
      app.MapWhen(
        context =>
        {
          // predicate to check if the request path matches the `physicalPath`
          if (!context.Request.Path.HasValue) return false;

          var path = context.Request.Path.Value.AsSpan();
          if (path.Length == 0) return false;
          if (path[0] == '/') path = path[1..];

          if (path.StartsWith(physicalPath, StringComparison.OrdinalIgnoreCase)) return true;

          var index = path.IndexOf("/", StringComparison.Ordinal);
          return index != -1 && path[(index + 1)..].StartsWith(physicalPath, StringComparison.OrdinalIgnoreCase);
        },
        c => c.UseSpa(spa =>
        {
          // use a PhysicalFileProvider that serves from the `physicalPath` as root.
          var sourcePath = Path.Combine(env.WebRootPath, physicalPath);
          spa.Options.SourcePath = sourcePath;
          spa.Options.DefaultPageStaticFileOptions = new StaticFileOptions
          {
            FileProvider = new PhysicalFileProvider(sourcePath)
          };
        })
      );
    }

  // map empty path to the the first app
  app.UseRewriter(new RewriteOptions().AddRedirect("^$", rootApps.First()));
}

if (env.IsDevelopment())
{
  app.UseDeveloperExceptionPage();
}

app.Run();

[Sayan751]

@javiercn Additional info: just in case, it was not clear from my last comment, the physical directory structure is as follows:

ConfiguredWebroot
+
+--+App1
|   +
|   +-+index.html
|   |
|   +-+other.static.resourc.es
|
+--+App2
    +
    +-+index.html
    |
    +-+other.static.resourc.es

[Sayan751]

Sorry if I am spamming. Here is some more info on this. In my attempt to isolate the issue, I tried the following instead of the .UseSpa.

c.Use((context, next) =>
{
  var ep = context.GetEndpoint();
  if (ep == null)
  {
    context.Request.Path = "/index.html";
  }
  return next(context);
});
c.UseStaticFiles(new StaticFileOptions
{
  FileProvider = new PhysicalFileProvider(sourcePath)
});

But that didn't help and the issue can still be reproduced.

[mkArtakMSFT]

@Tratcher, @halter73 is that expected to receive such a low-level exception? Maybe you see something suspicious in the call stack that should be investigated?

[Tratcher]

This appears similar to #35401, caused by client disconnects, but that should have been fixed in 6.0.

[Sayan751]

@Tratcher I have just ensured that I am using the latest versions of all the NuGets. However, I am still getting the error intermittently.