docker/cli · error · invalidParameterErr

insecure registry %s should not contain '://'

Error message

insecure registry %s should not contain '://'

What it means

Error "insecure registry %s should not contain '://'" thrown in docker/cli.

Source

Thrown at internal/registry/config.go:121

	// Localhost is by default considered as an insecure registry. This is a
	// stop-gap for people who are running a private registry on localhost.
	registries = append(registries, "::1/128", "127.0.0.0/8")

	var (
		insecureRegistryCIDRs = make([]*net.IPNet, 0)
		indexConfigs          = make(map[string]*registry.IndexInfo)
	)

skip:
	for _, r := range registries {
		if scheme, host, ok := strings.Cut(r, "://"); ok {
			switch strings.ToLower(scheme) {
			case "http", "https":
				log.G(context.TODO()).Warnf("insecure registry %[1]s should not contain '%[2]s' and '%[2]ss' has been removed from the insecure registry config", r, scheme)
				r = host
			default:
				// unsupported scheme
				return nil, invalidParam(fmt.Errorf("insecure registry %s should not contain '://'", r))
			}
		}
		// Check if CIDR was passed to --insecure-registry
		_, ipnet, err := net.ParseCIDR(r)
		if err == nil {
			// Valid CIDR. If ipnet is already in config.InsecureRegistryCIDRs, skip.
			for _, value := range insecureRegistryCIDRs {
				if value.IP.String() == ipnet.IP.String() && value.Mask.String() == ipnet.Mask.String() {
					continue skip
				}
			}
			// ipnet is not found, add it in config.InsecureRegistryCIDRs
			insecureRegistryCIDRs = append(insecureRegistryCIDRs, ipnet)
		} else {
			if err := validateHostPort(r); err != nil {
				return nil, invalidParam(fmt.Errorf("insecure registry %s is not valid: %w", r, err))
			}
			// Assume `host:port` if not CIDR.

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at internal/registry/config.go:121 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of docker/cli@e9452d6e78 (2026-08-01). Data as JSON: /data/errors/5c76e40a7a68e0b1.json. Report an issue: GitHub.