microsoft/aspire · error · ArgumentException

Endpoint ' ' for resource ' ' not found.

Error message

Endpoint '{0}' for resource '{1}' not found.

What it means

GetEndpointUriStringCore throws this ArgumentException when the requested endpoint name (or the implicit https/http fallback) cannot be resolved on the resource. After trying the explicit name or the https-then-http default pair, no EndpointReference matches, so the library fails fast.

Solutions

1. Use an endpoint name that the resource actually defines (check WithEndpoint/WithHttpEndpoint calls in the AppHost)
2. If the project is http-only, request "http" explicitly or omit scheme assumptions
3. Add the missing endpoint in the AppHost if the test legitimately needs it

Example fix

// before
var url = app.GetEndpoint("frontend", "https"); // http-only project
// after
var url = app.GetEndpoint("frontend", "http");

var res = (IResourceWithEndpoints)app.GetResource(name);
var endpoints = ((IResource)r).Annotations.OfType<EndpointAnnotation>().Select(a => a.Name).ToList();
// ensure desired endpoint name is in endpoints before calling GetEndpoint

try { var url = app.GetEndpoint(name, endpointName); }
catch (ArgumentException ex) when (ex.Message.Contains("not found"))
{
    // fall back to the other scheme or a different endpoint name
}

When it happens

Trigger: Calling app.GetEndpoint("frontend", "https") when the project only defines an http endpoint; calling without an endpoint name on a resource that has neither https nor http endpoints; using a custom endpoint name not registered via WithEndpoint.

Common situations: Projects configured http-only being asked for https; endpoint renamed in the AppHost (WithEndpoint(name: ...)) but tests still use the old name; endpoints only added conditionally.

Understand the failure class

Background: 'Could not be found', 'does not exist', 'not found in database': the resource-not-found family when an ID, slug, key, or URI lookup comes back empty — this error's family across 20 libraries.

Related errors

• Resource ' ' has no allocated endpoints.
• Resource ' ' does not expose a connection string.
• Resource ' ' not found.
• AllocatedEndpoint must use the same network as the…
• Array params contains empty item

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/f40a57eecbe9886e. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting.Testing/DistributedApplicationHostingTestingExtensions.cs:287

        {
            throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, Properties.Resources.ResourceHasNoAllocatedEndpointsExceptionMessage, resourceName), nameof(resourceName));
        }

        EndpointReference? endpoint;
        if (!string.IsNullOrEmpty(endpointName))
        {
            endpoint = GetEndpointOrDefault(resourceWithEndpoints, endpointName, networkIdentifier);
        }
        else
        {
            // Prefer https over http to match the default service discovery behavior (https+http://),
            // where https is tried first.
            endpoint = GetEndpointOrDefault(resourceWithEndpoints, "https", networkIdentifier) ?? GetEndpointOrDefault(resourceWithEndpoints, "http", networkIdentifier);
        }

        if (endpoint is null)
        {
            throw new ArgumentException(string.Format(CultureInfo.InvariantCulture, Properties.Resources.EndpointForResourceNotFoundExceptionMessage, endpointName, resourceName), nameof(endpointName));
        }

        return endpoint.Url;
    }

    static void ThrowIfNotStarted(DistributedApplication app, string exceptionMessage)
    {
        var lifetime = app.Services.GetRequiredService<IHostApplicationLifetime>();
        if (!lifetime.ApplicationStarted.IsCancellationRequested)
        {
            throw new InvalidOperationException(exceptionMessage);
        }
    }

    static EndpointReference? GetEndpointOrDefault(IResourceWithEndpoints resourceWithEndpoints, string endpointName, NetworkIdentifier? networkIdentifier = default)
    {
        var reference = resourceWithEndpoints.GetEndpoint(endpointName, networkIdentifier ?? KnownNetworkIdentifiers.LocalhostNetwork);

View on GitHub (pinned to 25830f84bd)