stack value is required but it was not passed or is empty

Error message

stack value is required but it was not passed or is empty

What it means

In `k6 cloud login`, the non-interactive branch activates when either -t/--token or --stack was passed. It then requires BOTH values; if the stack flag is absent (or passed but empty), login stops with this error before contacting the API. The stack may be a full URL (https://my-team.grafana.net) or a slug (my-team).

Solutions

Add the stack flag: `k6 cloud login -t <token> --stack my-team`
Or drop both flags and use the fully interactive prompt, which asks for token and stack in turn
In scripts, guard that both variables are non-empty before invoking k6 cloud login

Example fix

# before
k6 cloud login -t glc_ey...            # -> stack value is required

# after
k6 cloud login -t glc_ey... --stack my-team

Defensive patterns

Strategy: validation

Validate before calling

: "${K6_CLOUD_TOKEN:?token required}"
: "${K6_STACK:?stack required (slug or URL, e.g. my-team)}"
k6 cloud login -t "$K6_CLOUD_TOKEN" --stack "$K6_STACK"

Prevention

Remember the rule: if either -t or --stack is passed, BOTH are required
Default empty variables before interpolating flags in scripts
For exploratory use, run bare `k6 cloud login` and let the prompts guide you

When it happens

Trigger: Running `k6 cloud login -t <token>` without --stack, or `k6 cloud login --stack ""` — the switch case at cloud_login.go:105 fires because tokenInput is valid, then the stack check at line 106 fails.

Common situations: Muscle memory from older k6 where a token alone was enough; CI scripts updated half-way (token added, stack forgotten); empty stack variable interpolated into --stack "$STACK" with STACK unset.

Understand the failure class

Background: "--flag is required" and "must specify" CLI errors: how missing-required-flag validation works and how to fix it — this error's family across 20 libraries.

Related errors

AI-assisted analysis of grafana/k6@9cb32757e5 (2026-08-18). Data as JSON: /api/errors/4b35cc7c32026f2d. Report an issue: GitHub.

Appendix: source

Thrown at internal/cmd/cloud_login.go:107

	show := getNullBool(cmd.Flags(), "show")
	reset := getNullBool(cmd.Flags(), "reset")
	tokenInput := getNullString(cmd.Flags(), "token")
	stackInput := getNullString(cmd.Flags(), "stack")

	switch {
	case reset.Valid:
		newCloudConf.Token = null.StringFromPtr(nil)
		newCloudConf.StackID = null.IntFromPtr(nil)
		newCloudConf.StackURL = null.StringFromPtr(nil)
		newCloudConf.DefaultProjectID = null.IntFromPtr(nil)
		printToStdout(c.globalState, "\nToken and stack info have been reset.\n")
	case show.Bool:
		printConfig(c.globalState, newCloudConf)
		return nil
	case tokenInput.Valid || stackInput.Valid:
		if !stackInput.Valid || stackInput.String == "" {
			return errors.New("stack value is required but it was not passed or is empty")
		}
		if !tokenInput.Valid || tokenInput.String == "" {
			return errors.New("token value is required but it was not passed or is empty")
		}
		err := authenticateUserToken(c.globalState, &newCloudConf, currentJSONConfigRaw, tokenInput.String, stackInput.String)
		if err != nil {
			return err
		}
	default:
		gs := c.globalState

		userinfo, err := promptUserAuthForm(gs)
		if err != nil {
			return err
		}

		err = authenticateUserToken(gs, &newCloudConf, currentJSONConfigRaw,
			userinfo.token, userinfo.stack)

View on GitHub (pinned to 9cb32757e5)