microsoft/aspire · error · ArgumentNullException

Value cannot be null. (Parameter 'launchProfileName')

Error message

Value cannot be null. (Parameter 'launchProfileName')

What it means

DefaultLaunchProfileAnnotation's constructor performs a null check on launchProfileName and throws ArgumentNullException when it is null. The annotation exists to designate which launch settings profile a project resource should use, so a null name is meaningless.

Solutions

1. Provide a concrete profile name, e.g. "https" or "http".
2. Check the source value for null/empty before constructing the annotation and fall back to a default.
3. If the profile is optional, skip adding the annotation rather than adding one with a null name.

Example fix

// before
var profile = Environment.GetEnvironmentVariable("LAUNCH_PROFILE");
builder.AddAnnotation(new DefaultLaunchProfileAnnotation(profile)); // null -> throws
// after
var profile = Environment.GetEnvironmentVariable("LAUNCH_PROFILE") ?? "https";
builder.AddAnnotation(new DefaultLaunchProfileAnnotation(profile));

if (string.IsNullOrEmpty(profileName)) profileName = "https";
builder.AddAnnotation(new DefaultLaunchProfileAnnotation(profileName));

try { builder.AddAnnotation(new DefaultLaunchProfileAnnotation(profileName)); }
catch (ArgumentNullException) { /* skip or default profile */ }

When it happens

Trigger: Constructing new DefaultLaunchProfileAnnotation(null) — typically by passing a variable or configuration lookup that resolved to null, e.g. environment["PROFILE"] or an optional parameter.

Common situations: Reading the profile name from configuration/environment that is not set, refactoring a method to return a nullable string, or deserializing options where the field is missing.

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AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/63d87ea052c2784d. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/DefaultLaunchProfileAnnotation.cs:14

// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

using System.Diagnostics;

namespace Aspire.Hosting.ApplicationModel;

/// <summary>
/// An annotation that specifies the default launch profile for a resource.
/// </summary>
[DebuggerDisplay("Type = {GetType().Name,nq}, LaunchProfileName = {LaunchProfileName}")]
public sealed class DefaultLaunchProfileAnnotation(string launchProfileName) : IResourceAnnotation
{
    private readonly string _launchProfileName = launchProfileName ?? throw new ArgumentNullException(nameof(launchProfileName));

    /// <summary>
    /// The name of the default launch profile.
    /// </summary>
    public string LaunchProfileName => _launchProfileName;
}

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