grafana/k6 · error

Authentication failed as provided token or stack might not b

Error message

Authentication failed as provided token or stack might not be valid. Learn more: https://grafana.com/docs/grafana-cloud/testing/k6/author-run/tokens-and-cli-authentication. Server error for details: %w

What it means

During `k6 cloud login`, validateTokenV6 builds a v6 client and calls ValidateToken against the normalized stack URL; any failure (HTTP 401 for a bad token, wrong stack, or a network error) is wrapped in this user-facing message with a link to the token docs. The '%w' keeps the server's error detail, so the real reason is always appended after 'Server error for details: '.

Source

Thrown at internal/cmd/cloud_login.go:270

	gs *state.GlobalState,
	config *cloudapi.Config,
	rawConfig json.RawMessage,
	token, stack string,
) error {
	config.Token = null.StringFrom(token)
	consolidatedCurrentConfig, warn, err := cloudapi.GetConsolidatedConfig(
		rawConfig, gs.Env, "", nil)
	if err != nil {
		return err
	}
	if warn != "" {
		gs.Logger.Warn(warn)
	}

	stackURL, stackID, defaultProjectID, err := validateTokenV6(
		gs, consolidatedCurrentConfig, token, stack)
	if err != nil {
		return fmt.Errorf( //nolint:staticcheck // ST1005: this is a user-facing error
			"Authentication failed as provided token or stack might not be valid."+
				" Learn more: https://grafana.com/docs/grafana-cloud/testing/k6/author-run/tokens-and-cli-authentication."+
				" Server error for details: %w",

			err)
	}
	config.StackURL = null.StringFrom(stackURL)
	config.StackID = null.IntFrom(stackID)
	config.DefaultProjectID = null.IntFrom(defaultProjectID)

	return nil
}

// validateTokenV6 validates a token and a stack URL/slug and returns the normalized URL, stack ID,
// and default project ID.
// The stackInput can be either a full URL (e.g., https://my-team.grafana.net)
// or just a slug (e.g., my-team).
func validateTokenV6(

View on GitHub (pinned to 93accf6570)

Solutions

1. Read the text after 'Server error for details: ' — 401 means bad token/stack, network errors mean connectivity
2. Regenerate the API token and re-run `k6 cloud login --token <token>`
3. Double-check the stack argument: a full URL (https://my-team.grafana.net) or just the slug (my-team)
4. Verify proxy/firewall allows requests to the stack host

Example fix

# before
k6 cloud login --token 'eyJr... == '  # stray spaces, truncated
# after
k6 cloud login --token eyJr...==

if _, _, _, err := validateTokenV6(gs, conf, token, stack); err != nil {
    var re cloudapiv6.ResponseError
    if errors.As(err, &re) && re.Response.StatusCode == 401 {
        // permanent: token or stack wrong — regenerate and retry login once
    }
    // network-classified errors: retry login after checking connectivity
}

When it happens

Trigger: `k6 cloud login` with a revoked/expired API token, a token from a different org or stack, a mistyped stack slug, no network route to the API host, or a proxy mangling the request.

Common situations: Tokens pasted with whitespace or truncated by terminal wrapping; using a Grafana service-account token where a k6 Cloud token is required; wrong stack slug (typos, renamed orgs); corporate proxies blocking the validation endpoint.

Understand the failure class

• Authentication and authorization failures — expired tokens, bad credentials, and missing scopes.

Related errors

• token value is required but it was not passed or is empty
• Run `k6 cloud login` to authenticate, or check the docs for
• access token not configured
• stack value is required but it was not passed or is empty
• token cannot be empty

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/cb88caaa7758da56. Report an issue: GitHub.