microsoft/aspire · error · NotSupportedException

The endpoint(s) '"))} specify an unsupported transport. The…

Error message

The endpoint(s) {string.Join(", ", unsupportedEndpoints.Select(r => $"'{r.Endpoint.Name}'"))} specify an unsupported transport. The supported transports are 'http', 'http2', and 'tcp'.

What it means

Container Apps only support http, http2, and tcp transports for ingress/listeners. When generating Container App infrastructure, Aspire resolves all endpoints on the resource and throws this NotSupportedException if any endpoint's transport is outside that set (e.g., redis, udp, or a custom scheme's transport). The URI scheme is independent of transport, so a scheme like 'redis' is fine as long as transport is http or tcp.

Solutions

Set the endpoint transport explicitly to "tcp" for raw socket endpoints: .WithEndpoint(...).WithTransport("tcp").
Use http/http2 endpoints for HTTP-based ingress.
Remove the unsupported endpoint from the resource if it isn't needed in Container Apps.

Example fix

// before
.WithEndpoint(6379, endpoint => endpoint.Name = "redis"); // resolves to unsupported transport

// after
.WithEndpoint(6379, endpoint => endpoint.Name = "redis".WithTransport("tcp"));
// or: .WithEndpoint(name: "redis", port: 6379, scheme: null).WithTransport("tcp")

Defensive patterns

Strategy: validation

Validate before calling

var bad = resource.GetEndpoints().Where(e => e.Endpoint.Transport is not ("http" or "http2" or "tcp"));
if (bad.Any()) throw new InvalidOperationException($"Unsupported transports: {string.Join(',', bad.Select(b => b.Endpoint.Name))}");

Type guard

bool IsContainerAppsTransport(string? t) => t is "http" or "http2" or "tcp";

Try / catch

try { /* build/publish */ } catch (NotSupportedException ex) when (ex.Message.Contains("unsupported transport")) { /* fix endpoint transports */ }

Prevention

For raw socket services (redis, databases), always set transport explicitly to tcp.
Remember scheme (redis, rediss) is independent of transport; validate both.
Run aspire publish/generate locally in CI before deploying.

When it happens

Trigger: Calling WithEndpoint/WithHttpEndpoint/WithHttpsEndpoint with an explicit transport other than http/http2/tcp, or a custom endpoint (e.g., WithEndpoint(name: "redis", port: 6379) on a resource whose default transport resolution yields an unsupported value) on a project/container resource published to Container Apps.

Common situations: Exposing database/cache endpoints (redis, postgres) with scheme-based transports; porting endpoints defined with WithEndpoint(endpointName, scheme: "redis") defaults that map to a non-TCP transport; third-party extension resources declaring exotic transports.

Related errors

AI-assisted analysis of microsoft/aspire@25830f84bd (2026-09-16). Data as JSON: /api/errors/87243452cddb8faa. Report an issue: GitHub.

Appendix: source

Thrown at src/Aspire.Hosting.Azure.AppContainers/ContainerAppContext.cs:149

    }

    protected override void ProcessEndpoints()
    {
        // Resolve endpoint ports using the centralized helper
        var resolvedEndpoints = Resource.ResolveEndpoints();

        if (resolvedEndpoints.Count == 0)
        {
            return;
        }

        // Validate transport layer: only http-based and tcp transports are supported by Container Apps.
        // The URI scheme (e.g. "redis", "rediss", "foo") is independent of transport.
        var unsupportedEndpoints = resolvedEndpoints.Where(r => r.Endpoint.Transport is not ("http" or "http2" or "tcp")).ToArray();

        if (unsupportedEndpoints.Length > 0)
        {
            throw new NotSupportedException($"The endpoint(s) {string.Join(", ", unsupportedEndpoints.Select(r => $"'{r.Endpoint.Name}'"))} specify an unsupported transport. The supported transports are 'http', 'http2', and 'tcp'.");
        }

        // Group resolved endpoints by target port (aka destinations), this gives us the logical bindings or destinations
        var endpointsByTargetPort = resolvedEndpoints
            .Select((resolved, index) => (resolved, index))
            .GroupBy(x => x.resolved.TargetPort.Value)
            .Select(g => new
            {
                Port = g.Key,
                ResolvedEndpoints = g.Select(x => x.resolved).ToArray(),
                External = g.Any(x => x.resolved.Endpoint.IsExternal),
                IsHttpOnly = g.All(x => x.resolved.Endpoint.Transport is "http" or "http2"),
                AnyH2 = g.Any(x => x.resolved.Endpoint.Transport is "http2"),
                UniqueTransports = g.Select(x => x.resolved.Endpoint.Transport).Distinct().ToArray(),
                Index = g.Min(x => x.index)
            })
            .ToList();

View on GitHub (pinned to 25830f84bd)