caddyserver/caddy · warning

no admin server

Error message

no admin server

What it means

stopAdminServer guards against being handed a nil *http.Server when shutting down the previous admin endpoint during a config change. In practice this is an internal invariant — the admin server pointer must exist to be stopped — and nil here indicates a bookkeeping bug or a custom embedder calling it with no server running.

Source

Thrown at admin.go:740

	}
}

func adminPathAllowed(reqPath, allowedPath string) bool {
	if allowedPath == "" || allowedPath == "/" {
		return strings.HasPrefix(reqPath, allowedPath)
	}
	if reqPath == allowedPath {
		return true
	}
	if strings.HasSuffix(allowedPath, "/") {
		return strings.HasPrefix(reqPath, allowedPath)
	}
	return strings.HasPrefix(reqPath, allowedPath+"/")
}

func stopAdminServer(srv *http.Server) error {
	if srv == nil {
		return fmt.Errorf("no admin server")
	}
	timeout := 10 * time.Second
	ctx, cancel := context.WithTimeoutCause(context.Background(), timeout, fmt.Errorf("stopping admin server: %ds timeout", int(timeout.Seconds())))
	defer cancel()
	err := srv.Shutdown(ctx)
	if err != nil {
		if cause := context.Cause(ctx); cause != nil && errors.Is(err, context.DeadlineExceeded) {
			err = cause
		}
		return fmt.Errorf("shutting down admin server: %v", err)
	}
	Log().Named("admin").Info("stopped previous server", zap.String("address", srv.Addr))
	return nil
}

// AdminRouter is a type which can return routes for the admin API.
type AdminRouter interface {
	Routes() []AdminRoute

View on GitHub (pinned to 50e54ee279)

Solutions

1. If admin was disabled ('admin off'), keep it disabled across config changes or fully re-enable it rather than toggling mid-process
2. Update to the latest Caddy patch release; nil-server shutdown paths have been hardened over time
3. If reproducible on a stock binary, open an upstream bug with the config sequence

When it happens

Trigger: Caddy internals calling stopAdminServer(nil) during config replacement when no admin server was ever started (e.g. admin disabled via 'admin off' followed by a config that enables remote admin); library users invoking unexported paths via unsafe tricks.

Common situations: Configs mixing 'admin off' and later remote admin enabling in the same process; extremely rare with stock binaries — if seen, likely a bug worth reporting upstream.

Related errors

• no metrics registry found
• loading identity issuer modules: %s
• access control %d public key %d: parsing base64 certificate
• cannot enable remote admin without a certificate cache; conf
• no identifiers configured

AI-assisted analysis of caddyserver/caddy@50e54ee279 (2026-08-15). Data as JSON: /api/errors/fdbdb74f2dee14e1. Report an issue: GitHub.