`Hosting failed to start` inside VS Code dev container with quickstart

[erwinkramer]

Is there an existing issue for this?

• I have searched the existing issues

Describe the bug

Hosting failed to start inside VS Code Dev Container with the Aspire quickstart.

Locally, without dev container setup, but with the quickstart, I don't have an issue.

Expected Behavior

Should just run.

Steps To Reproduce

Start Docker Desktop Version 4.74.0 (227015) on Windows (11), enable WSL integration in the Docker Desktop settings.

Make a project with the quickstart:

aspire new aspire-starter -n AspireApp -o AspireApp

Then add the devcontainer setup from: https://github.com/microsoft/aspire-devcontainer/blob/main/.devcontainer/devcontainer.json

I omitted some parts from the config sample, so it looks like:

{
	"name": "Aspire",
	// Or use a Dockerfile or Docker Compose file. More info: https://containers.dev/guide/dockerfile
	"image": "mcr.microsoft.com/devcontainers/dotnet:dev-10.0-noble",
	"features": {
		"ghcr.io/microsoft/aspire-devcontainer-feature/aspire:2": {},
		"ghcr.io/devcontainers/features/docker-in-docker:2": {}
	},
	// Use 'forwardPorts' to make a list of ports inside the container available locally.
	// "forwardPorts": [5000, 5001],
	// "portsAttributes": {
	//		"5001": {
	//			"protocol": "https"
	//		}
	// }

	// Use 'postCreateCommand' to run commands after the container is created.
	// "postCreateCommand": "dotnet restore",
	"postStartCommand": "dotnet dev-certs https --trust",
	"customizations": {
		"vscode": {
			"extensions": [
				"ms-dotnettools.csdevkit",
				"GitHub.copilot-chat",
				"microsoft-aspire.aspire-vscode"
			]
		}
	}
}

Then reopen in dev container (vscode), and run the AppHost project.

Exceptions (if any)

📂  Launching Aspire debug session for AppHost /workspaces/New folder/HelloAspire/HelloAspire.AppHost/AppHost.cs...
Finding AppHosts...
HelloAspire.AppHost.csproj
🔐 Trusting certificates...
⚠️ Developer certificates may not be fully trusted (trust exit code was: PartiallyFailedToTrustTheCertificate).
🛠️ Building AppHost... HelloAspire.AppHost.csproj
🔬 Checking project type...: HelloAspire.AppHost.csproj
Connecting to AppHost...
info: Aspire.Hosting.DistributedApplication[0]
      Aspire version: 13.3.5+70b33bcb5f64c75e3ab6f57616545f35bd43dc81
info: Aspire.Hosting.DistributedApplication[0]
      Distributed application starting.
info: Aspire.Hosting.DistributedApplication[0]
      Application host directory is: /workspaces/New folder/HelloAspire/HelloAspire.AppHost
warn: Microsoft.AspNetCore.DataProtection.Repositories.FileSystemXmlRepository[60]
      Storing keys in a directory '/home/vscode/.aspnet/DataProtection-Keys' that may not be persisted outside of the container. Protected data will be unavailable when container is destroyed. For more information go to https://aka.ms/aspnet/dataprotectionwarning
warn: Microsoft.AspNetCore.DataProtection.KeyManagement.XmlKeyManager[35]
      No XML encryptor configured. Key {3d571bdf-60f9-470c-87e0-865b88cec534} may be persisted to storage in unencrypted form.
fail: Microsoft.Extensions.Hosting.Internal.Host[11]
      Hosting failed to start
      System.Threading.Tasks.TaskCanceledException: A task was canceled.
         at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.BindAsync(CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
         at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__14_1(IHostedService service, CancellationToken token)
         at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)
fail: Microsoft.Extensions.Hosting.Internal.Host[11]
      Hosting failed to start
      System.Threading.Tasks.TaskCanceledException: A task was canceled.
         at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.BindAsync(CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Server.Kestrel.Core.KestrelServerImpl.StartAsync[TContext](IHttpApplication`1 application, CancellationToken cancellationToken)
         at Microsoft.AspNetCore.Hosting.GenericWebHostService.StartAsync(CancellationToken cancellationToken)
         at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__14_1(IHostedService service, CancellationToken token)
         at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)
         at Microsoft.Extensions.Hosting.Internal.Host.StartAsync(CancellationToken cancellationToken)
         at Aspire.Hosting.Dashboard.DashboardServiceHost.Microsoft.Extensions.Hosting.IHostedService.StartAsync(CancellationToken cancellationToken) in /_/src/Aspire.Hosting/Dashboard/DashboardServiceHost.cs:line 205
         at Microsoft.Extensions.Hosting.Internal.Host.<StartAsync>b__14_1(IHostedService service, CancellationToken token)
         at Microsoft.Extensions.Hosting.Internal.Host.ForeachService[T](IEnumerable`1 services, CancellationToken token, Boolean concurrent, Boolean abortOnFirstException, List`1 exceptions, Func`3 operation)
ℹ️  The AppHost process has terminated. To view console output, select the AppHost session from the debug console dropdown.
🔌  Disconnecting from Aspire debug session... Child processes will be stopped.

Aspire doctor output

This is the output when running the command inside the dev container from vs code.

Aspire Environment Check
========================

.NET SDK
  ✅ .NET 10.0.300 installed (x64)  

Container Runtime
  ✅ Docker: running (auto-detected (default)) ← active  

Environment
  ✅ WSL2 environment detected  
       Details:                                                                                                 
       If you experience container connectivity issues, ensure Docker Desktop WSL integration is enabled.       
  ⚠️ HTTPS development certificate is only partially trusted  
       Set SSL_CERT_DIR in your shell profile: export                                                                      
       SSL_CERT_DIR="$SSL_CERT_DIR:/usr/lib/ssl/certs:/home/vscode/.aspnet/dev-certs/trust"                                
       See: https://aka.ms/aspire-prerequisites#dev-certs                                                                  
       Details:                                                                                                            
       The certificate is in the trusted store, but SSL_CERT_DIR is not configured to include                              
       '/home/vscode/.aspnet/dev-certs/trust'. Some applications may not trust the certificate. 'aspire run' will          
       configure this automatically.                                                                                       

Summary: 3 passed, 1 warnings, 0 failed
For detailed prerequisites: https://aka.ms/aspire-prerequisites

Anything else?

Also tried the podman setup, until I got hit with the same Hosting failed to start. It required me to use the following VS Code settings before I got there:

    "dev.containers.dockerPath": "podman",
    "dev.containers.dockerComposePath": "podman compose",
    "dev.containers.mountWaylandSocket": false,

And the following extra devcontainer setting:

   "remoteUser": "root"

Using podman version 5.8.2

Also tried .NET 11 preview, via mcr.microsoft.com/devcontainers/dotnet:dev-11.0-preview-resolute, which works great for .NET 11 projects, except for Aspire, giving the same host failed to start message.

[joperezr]

🤖 Aspire triage pass — 2026-05-21 15:13 UTC

Area: area-dashboard, area-app-model
Kind: bug
Repro: yes-minimal — see the devcontainer config and reproduction steps in the issue body
Affected version(s): 13.3.5 (latest servicing: 13.3.x line)
Severity: S2 — quickstart fails to start inside the official Aspire devcontainer; dashboard's Kestrel BindAsync is canceled at DashboardServiceHost.cs:line 205. No workaround surfaced by reporter.

Urgency: 🟡 vNext — recommend milestone 13.4
Reason: S2 hosting failure with a clean repro, but scoped to devcontainer environment; no evidence yet that this worked in 13.2 (so not confidently a servicing regression).

Suggested owner(s): James Newton-King (@JamesNK) (score 11), backup Adam Ratzman (@adamint) (score 2)
Evidence:

• JamesNK merged 33 PRs labeled area-dashboard in the last 90 days (top contributor by a wide margin)
• JamesNK also merged 13 PRs labeled area-app-model in the last 90 days
• adamint merged 2 PRs labeled area-dashboard in the last 90 days
• Failure stack originates in src/Aspire.Hosting/Dashboard/DashboardServiceHost.cs (per-issue stack trace)

Confidence: medium
Needs human?: yes — confirm whether this is a devcontainer-only regression vs. a Kestrel/startup race; a human should decide if 13.3.x servicing is warranted.

Dry-run mode — no labels or milestone applied. Reply /triage apply to promote, or edit and reapply.

[ellahathaway]

I verified the root cause and fix against the published Aspire 13.5.0 release.

Environment:

• mcr.microsoft.com/devcontainers/dotnet:dev-10.0-noble on Linux ARM64
• .NET SDK 10.0.400
• Aspire CLI/AppHost 13.5.0+e076d8e427cb3afb528dbd605acd74c3aea69f94
• The container was resumed after being stopped, preserving the suspend/resume condition implicated in the original failure.

Results:

1. A normal 13.5.0 AppHost launch completed and produced a working dashboard login URL.
2. I then ran a deterministic process-identity check with:
   • a live parent PID;
   • ASPIRE_CLI_STARTED=1, deliberately stale; and
   • the correct ASPIRE_CLI_STARTED_STABLE value derived from that same process's Linux /proc start ticks.
3. The 13.5.0 AppHost logged Using stable start time verification, remained running, and exposed a working dashboard login URL. It did not log CLI process ... is no longer running, Hosting failed to start, or the Kestrel TaskCanceledException.

For comparison, the equivalent pre-13.5 check with Aspire 13.4.6 selected the legacy timestamp, treated the same live parent as gone, and reproduced the reported Kestrel cancellation.

This confirms that Aspire 13.5 fixes the false orphan detection by preferring the stable process identity. Updating the Aspire CLI/AppHost to 13.5 or newer avoids this failure.

The partial development-certificate trust warning was also present during the successful 13.5 runs, so it is not the cause of this startup cancellation.

I am keeping this issue open while preparing a follow-up VS Code extension change that warns users when their Aspire CLI predates 13.5. PR #19447 was closed in favor of that warning-based approach.

[ellahathaway]

Resolved with #19670 and #19854