grafana/k6 · error

invalid compatibility mode "%s". Use: "%s"

Error message

invalid compatibility mode "%s". Use: "%s"

What it means

Raised by ValidateCompatibilityMode when the K6_COMPATIBILITY_MODE value (or --compatibility-mode flag) is not one of the supported JavaScript compatibility modes. The message lists the valid values.

Source

Thrown at lib/runtime_options.go:62

	SummaryExport null.String `json:"summaryExport"`
	KeyWriter     null.String `json:"-"`
	TracesOutput  null.String `json:"tracesOutput"`

	// Until v2
	NewMachineReadableSummary null.Bool `json:"newMachineReadableSummary"`
}

// ValidateCompatibilityMode checks if the provided val is a valid compatibility mode
func ValidateCompatibilityMode(val string) (cm CompatibilityMode, err error) {
	if val == "" {
		return CompatibilityModeExtended, nil
	}
	if cm, err = CompatibilityModeString(val); err != nil {
		var compatValues []string
		for _, v := range CompatibilityModeValues() {
			compatValues = append(compatValues, v.String())
		}
		err = fmt.Errorf(`invalid compatibility mode "%s". Use: "%s"`,
			val, strings.Join(compatValues, `", "`))
	}
	return cm, err
}

View on GitHub (pinned to 01ffac6f24)

Solutions

1. Use one of: extended, base, default (unsafe-compat) — typically "extended" or "base"
2. Check for typos in the flag or environment variable

When it happens

Trigger: Thrown at lib/runtime_options.go:62 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of grafana/k6@01ffac6f24 (2026-08-18). Data as JSON: /api/errors/fa50168d8dfbe00f. Report an issue: GitHub.