slackhq/nebula · error

not a valid logging level: %q

Error message

not a valid logging level: %q

What it means

ParseLevel converts a string log level to slog.Level and returns this error for unrecognized strings. Accepted values include debug/info/warn/warning/error/fatal/panic (per the switch); everything else fails. Called by ApplyConfig and sshLogLevel.

Source

Thrown at logging/logger.go:214

// "warn"/"warning", "error", "fatal"/"panic") to a slog.Level. "fatal" and
// "panic" are accepted for backwards compatibility with pre-slog configs
// and both map to slog.LevelError.
func ParseLevel(s string) (slog.Level, error) {
	switch s {
	case "trace":
		return LevelTrace, nil
	case "debug":
		return slog.LevelDebug, nil
	case "info":
		return slog.LevelInfo, nil
	case "warn", "warning":
		return slog.LevelWarn, nil
	case "error":
		return slog.LevelError, nil
	case "fatal", "panic":
		return slog.LevelError, nil
	default:
		return 0, fmt.Errorf("not a valid logging level: %q", s)
	}
}

// LevelName returns a human-readable name for a slog.Level matching the
// strings accepted by ParseLevel.
func LevelName(l slog.Level) string {
	switch {
	case l <= LevelTrace:
		return "trace"
	case l <= slog.LevelDebug:
		return "debug"
	case l <= slog.LevelInfo:
		return "info"
	case l <= slog.LevelWarn:
		return "warn"
	default:
		return "error"
	}

View on GitHub (pinned to dd8f660c0a)

Solutions

1. Use a supported level string: debug, info, warn/warning, error, fatal/panic
2. Trim and lowercase the level string before parsing
3. Remove stray quotes/whitespace in the YAML value

Example fix

// before
lvl, err := logging.ParseLevel("trace")
// after
s, err2 := sanitize(level)
if err2 != nil { return err2 }
lvl, err := logging.ParseLevel(strings.ToLower(strings.TrimSpace(s)))

lvl, err := logging.ParseLevel(strings.ToLower(strings.TrimSpace(cfgLevel)))
if err != nil {
    lvl = slog.LevelInfo // or fail fast
}

When it happens

Trigger: Setting a level in config or via SSH console (sshLogLevel) such as 'verbose', 'trace', 'WARN ' (whitespace), or a numeric level string that the switch does not handle.

Common situations: Using 'trace' or 'verbose' from other tools' conventions; trailing whitespace/quotes in YAML; case-sensitive input like 'DEBUG'.

Related errors

• unknown log format `%s`. possible formats: %s
• unknown protocol %v
• %s failed to parse, should be an array of rules
• %s rule #%v; only one of port or code should be provided
• %s rule #%v; at least one of host, group, cidr, local_cidr,

AI-assisted analysis of slackhq/nebula@dd8f660c0a (2026-09-03). Data as JSON: /api/errors/4b689c94fcd9d95a. Report an issue: GitHub.