microsoft/aspire · error · DistributedApplicationException

The endpoint ' ' does not exist on the resource ' '.

Error message

The endpoint '{endpointName}' does not exist on the resource '{builder.Resource.Name}'.

What it means

Thrown from the OnResourceEndpointsAllocated callback registered by WithHttpHealthCheck when, after endpoint allocation, endpoint.Exists is false — i.e. the endpoint name referenced by the health check was never allocated on the resource. Aspire validates late (during allocation) to fail fast on misconfiguration before the health check runs.

Solutions

1. Ensure the endpoint with that name exists: add WithHttpEndpoint(name: ...)/WithEndpoint matching the health-check name.
2. Update the health-check call to use the current endpoint name after renames.
3. Remove environment-conditional endpoint creation or make the health check conditional too.
4. Run the AppHost and check allocated endpoints in the dashboard to confirm the name/scheme.

Example fix

// before
var api = builder.AddProject<Projects.Api>("api")
    .WithHttpEndpoint(name: "web");
api.WithHttpHealthCheck("http"); // throws: 'http' not allocated

// after
var api = builder.AddProject<Projects.Api>("api")
    .WithHttpEndpoint(name: "web");
api.WithHttpHealthCheck("web");

var names = resource.Annotations.OfType<EndpointAnnotation>().Select(e => e.Name);
if (!names.Contains(endpointName))
    Console.Warn($"Endpoint '{endpointName}' not declared on resource.");

bool EndpointDeclared(IResource r, string name) => r.Annotations.OfType<EndpointAnnotation>().Any(e => string.Equals(e.Name, name, StringComparison.OrdinalIgnoreCase));

try { appHost.Run(); }
catch (DistributedApplicationException ex) when (ex.Message.Contains("does not exist on the resource"))
{ Console.Error.WriteLine($"Fix endpoint name: {ex.Message}"); throw; }

When it happens

Trigger: WithHttpHealthCheck(endpointName) where the named endpoint doesn't exist on the resource; endpoint declared conditionally (only in some environments); endpoint removed/renamed while the health check still references the old name; scheme/name mismatch so no matching endpoint is allocated.

Common situations: Renaming an endpoint in the AppHost but not the health-check call; environment-specific endpoint creation; project references a port/endpoint that only exists in another project.

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

• Could not create HTTP health check for resource
• Could not create HTTP health check for resource
• Connection string is unavailable
• Connection string is unavailable
• Connection string is unavailable

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/c3a6420944ea0dfa. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting/ResourceBuilderExtensions.cs:2826

        var endpoint = endpointSelector()
            ?? throw new DistributedApplicationException($"Could not create HTTP health check for resource '{builder.Resource.Name}' as the endpoint selector returned null.");

        if (endpoint.Scheme != "http" && endpoint.Scheme != "https")
        {
            throw new DistributedApplicationException($"Could not create HTTP health check for resource '{builder.Resource.Name}' as the endpoint with name '{endpoint.EndpointName}' and scheme '{endpoint.Scheme}' is not an HTTP endpoint.");
        }

        path ??= "/";
        statusCode ??= 200;

        var endpointName = endpoint.EndpointName;

        // Validate that the endpoint exists during allocation to fail fast on misconfiguration.
        builder.OnResourceEndpointsAllocated((_, @event, ct) =>
        {
            if (!endpoint.Exists)
            {
                throw new DistributedApplicationException($"The endpoint '{endpointName}' does not exist on the resource '{builder.Resource.Name}'.");
            }

            return Task.CompletedTask;
        });

        var healthCheckKey = $"{builder.Resource.Name}_{endpointName}_{path}_{statusCode}_check";

        builder.ApplicationBuilder.Services.AddHttpClient();
        builder.ApplicationBuilder.Services.SuppressHealthCheckHttpClientLogging(healthCheckKey);

        builder.ApplicationBuilder.Services.AddHealthChecks().Add(new HealthCheckRegistration(
            healthCheckKey,
            serviceProvider => new EndpointUriHealthCheck(
                endpoint,
                path,
                statusCode.Value,
                () => serviceProvider.GetRequiredService<IHttpClientFactory>().CreateClient(healthCheckKey)),
            failureStatus: default,

View on GitHub (pinned to 25830f84bd)