docker/compose · error

unsupported network: %s

Error message

unsupported network: %s

What it means

The lower-level memnet.Dial switch only implements the "unix" and "npipe" networks; any other network string ("tcp", "udp", an empty string, "UNIX" with wrong case) hits the default arm and fails immediately without dialing. This is separate from error 87: DialEndpoint parses the scheme and calls Dial with the canonical network name, so seeing this from DialEndpoint means the scheme matched but was mapped unexpectedly — more often it appears when code calls Dial directly.

Source

Thrown at internal/memnet/conn.go:48

	if addr, ok := strings.CutPrefix(endpoint, "npipe://"); ok {
		return Dial(ctx, "npipe", addr)
	}
	return nil, fmt.Errorf("unsupported protocol for address: %s", endpoint)
}

func Dial(ctx context.Context, network, addr string) (net.Conn, error) {
	var d net.Dialer
	switch network {
	case "unix":
		if err := validateSocketPath(addr); err != nil {
			return nil, err
		}
		return d.DialContext(ctx, "unix", addr)
	case "npipe":
		// N.B. this will return an error on non-Windows
		return dialNamedPipe(ctx, addr)
	default:
		return nil, fmt.Errorf("unsupported network: %s", network)
	}
}

View on GitHub (pinned to ddc4b044b6)

Solutions

1. Pass one of the two supported network names: Dial(ctx, "unix", "/path/to.sock") or Dial(ctx, "npipe", pipeName) on Windows.
2. For TCP endpoints, use net.Dialer.DialContext directly — memnet intentionally does not support it.
3. Centralize the scheme→network mapping in one place (as DialEndpoint does) instead of ad-hoc call sites.

Example fix

// before
conn, err := memnet.Dial(ctx, "tcp", "127.0.0.1:2375") // unsupported

// after
conn, err := (&net.Dialer{}).DialContext(ctx, "tcp", "127.0.0.1:2375")

switch network {
case "unix", "npipe": // ok
default:
    return fmt.Errorf("memnet supports unix/npipe, got %q", network)
}
conn, err := memnet.Dial(ctx, network, addr)

func supportedNetwork(n string) bool { return n == "unix" || n == "npipe" }

conn, err := memnet.Dial(ctx, network, addr)
if err != nil {
    return fmt.Errorf("memnet dial %s %s: %w", network, addr, err)
}

When it happens

Trigger: Calling memnet.Dial(ctx, network, addr) with network other than exactly "unix" or "npipe" — e.g. "tcp", "tcp4", "", or a scheme string like "unix://" passed as the network argument by mistake.

Common situations: Reusing a generic dial helper that passes scheme:// strings where a bare network name is expected; empty network after defaults are applied incorrectly; copied code that assumed net.Dial's accepted networks.

Related errors

• unsupported protocol for address: %s
• named pipes are only available on Windows
• socket address is too long: %s
• invalid digest %s: %w
• invalid PID (%d): only positive PIDs are allowed

AI-assisted analysis of docker/compose@ddc4b044b6 (2026-08-15). Data as JSON: /api/errors/cc976d961718fc91. Report an issue: GitHub.