grafana/k6 · error

stack ID %d overflows int32

Error message

stack ID %d overflows int32

What it means

SetStackID rejects a stack ID that does not fit in a signed 32-bit integer. The underlying k6 Cloud OpenAPI Go SDK sends the stack ID as the X-Stack-Id header, which is typed int32, so the client validates the int64 configuration value before narrowing it. In the CLI this value comes from the consolidated cloud configuration (flags, K6_CLOUD_STACK_ID, or the on-disk config written by `k6 cloud login`).

Source

Thrown at internal/cloudapi/v6/client.go:50

	}

	cfg := clientcfg.New(host, version, "Global k6 Cloud API.", timeout)

	c := &Client{
		apiClient: k6cloud.NewAPIClient(cfg),
		token:     token,
		baseURL:   fmt.Sprintf("%s/cloud/v6", host),
		logger:    logger,
	}
	return c, nil
}

// SetStackID sets the stack ID for the client. It returns an error if
// stackID does not fit in the int32 range the underlying SDK requires for
// the X-Stack-Id header.
func (c *Client) SetStackID(stackID int64) error {
	if stackID < math.MinInt32 || stackID > math.MaxInt32 {
		return fmt.Errorf("stack ID %d overflows int32", stackID)
	}
	c.stackID = int32(stackID)
	return nil
}

// BaseURL returns configured host.
func (c *Client) BaseURL() string {
	return c.baseURL
}

// CheckResponse checks the parsed response.
// It returns nil if the code is in the successful range,
// otherwise it tries to parse the body and return a parsed error.
func CheckResponse(r *http.Response, err error) error {
	if err != nil {
		var aerr *k6cloud.GenericOpenAPIError
		if !errors.As(err, &aerr) {
			return err

View on GitHub (pinned to 93accf6570)

Solutions

1. Re-run `k6 cloud login` so the server returns and stores the correct stack ID
2. Fix or unset K6_CLOUD_STACK_ID; real stack IDs are small integers, not billions
3. Check the on-disk cloud config (read via readDiskConfig) for a bad stack-id value and correct it
4. If calling SetStackID from Go code, range-check the value against math.MinInt32/math.MaxInt32 first

Example fix

# before
K6_CLOUD_STACK_ID=5000000000 k6 cloud script.js
# after
K6_CLOUD_STACK_ID=1234567 k6 cloud script.js

stackID, err := strconv.ParseInt(os.Getenv("K6_CLOUD_STACK_ID"), 10, 64)
if err != nil || stackID < math.MinInt32 || stackID > math.MaxInt32 {
    log.Fatalf("invalid K6_CLOUD_STACK_ID: must be an int32-range integer")
}

func isValidStackID(id int64) bool {
    return id >= math.MinInt32 && id <= math.MaxInt32
}

When it happens

Trigger: Calling cloudapiv6.Client.SetStackID with stackID < math.MinInt32 or > math.MaxInt32 (e.g. 5000000000). Via the CLI: any cloud command whose resolved K6_CLOUD_STACK_ID or stored login config contains a corrupted or mistyped number.

Common situations: CI pipelines that template the wrong variable (a project or org ID instead of the stack ID); a typo or truncated-then-garbage value in K6_CLOUD_STACK_ID; a hand-edited or stale config.json from an older k6 version.

Related errors

• stack URL is required to validate token
• 104
• sigV4 config `Region`, `AwsAccessKeyID`, `AwsSecretAccessKey
• failed to parse retryable status codes: %w
• create or find load test: %w

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/d3a720283e168029. Report an issue: GitHub.