grafana/k6 · error

the duration is unspecified

Error message

the duration is unspecified

What it means

ConstantVUsConfig.Validate found 'duration' unset. The constant-VUs executor has no natural end condition — VUs loop until the fixed duration elapses — so the option is required, unlike executors with iteration counts.

Source

Thrown at lib/executor/constant_vus.go:72

func (clvc ConstantVUsConfig) GetVUs(et *lib.ExecutionTuple) int64 {
	return et.ScaleInt64(clvc.VUs.Int64)
}

// GetDescription returns a human-readable description of the executor options
func (clvc ConstantVUsConfig) GetDescription(et *lib.ExecutionTuple) string {
	return fmt.Sprintf("%d looping VUs for %s%s",
		clvc.GetVUs(et), clvc.Duration.Duration, clvc.getBaseInfo())
}

// Validate makes sure all options are configured and valid
func (clvc ConstantVUsConfig) Validate() []error {
	errors := clvc.BaseConfig.Validate()
	if clvc.VUs.Int64 <= 0 {
		errors = append(errors, fmt.Errorf("the number of VUs must be more than 0"))
	}

	if !clvc.Duration.Valid {
		errors = append(errors, fmt.Errorf("the duration is unspecified"))
	} else if clvc.Duration.TimeDuration() < minDuration {
		errors = append(errors, fmt.Errorf(
			"the duration must be at least %s, but is %s", minDuration, clvc.Duration,
		))
	}

	return errors
}

// GetExecutionRequirements returns the number of required VUs to run the
// executor for its whole duration (disregarding any startTime), including the
// maximum waiting time for any iterations to gracefully stop. This is used by
// the execution scheduler in its VU reservation calculations, so it knows how
// many VUs to pre-initialize.
func (clvc ConstantVUsConfig) GetExecutionRequirements(et *lib.ExecutionTuple) []lib.ExecutionStep {
	return []lib.ExecutionStep{
		{
			TimeOffset: 0,

View on GitHub (pinned to 01ffac6f24)

Solutions

1. Add duration to the scenario, e.g. duration: '10m'
2. For a fixed number of iterations use per-vu-iterations or shared-iterations instead

When it happens

Trigger: Thrown at lib/executor/constant_vus.go:72 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/70d14ce92ec5ce8e. Report an issue: GitHub.