docker/cli · error

invalid label '%s': empty name

Error message

invalid label '%s': empty name

What it means

Error "invalid label '%s': empty name" thrown in docker/cli.

Source

Thrown at opts/opts.go:243

const whiteSpaces = " \t"

// ValidateLabel validates that the specified string is a valid label, and returns it.
//
// Labels are in the form of key=value; key must be a non-empty string, and not
// contain whitespaces. A value is optional (defaults to an empty string if omitted).
//
// Leading whitespace is removed during validation but values are kept as-is
// otherwise, so any string value is accepted for both, which includes whitespace
// (for values) and quotes (surrounding, or embedded in key or value).
//
// TODO discuss if quotes (and other special characters) should be valid or invalid for keys
// TODO discuss if leading/trailing whitespace in keys should be preserved (and valid)
func ValidateLabel(value string) (string, error) {
	key, _, _ := strings.Cut(value, "=")
	key = strings.TrimLeft(key, whiteSpaces)
	if key == "" {
		return "", fmt.Errorf("invalid label '%s': empty name", value)
	}
	if strings.ContainsAny(key, whiteSpaces) {
		return "", fmt.Errorf("label '%s' contains whitespaces", key)
	}
	return value, nil
}

// ValidateSysctl validates a sysctl and returns it.
func ValidateSysctl(val string) (string, error) {
	validSysctlMap := map[string]bool{
		"kernel.msgmax":          true,
		"kernel.msgmnb":          true,
		"kernel.msgmni":          true,
		"kernel.sem":             true,
		"kernel.shmall":          true,
		"kernel.shmmax":          true,
		"kernel.shmmni":          true,
		"kernel.shm_rmid_forced": true,

View on GitHub (pinned to e9452d6e78)

When it happens

Trigger: Thrown at opts/opts.go:243 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/c85cd13765b2f5b2.json. Report an issue: GitHub.