grafana/k6 · error

unpacking selected options

Error message

unpacking selected options: %w

What it means

Internal error in the k6 browser module's ElementHandle.selectOption(). After the in-page selectOptions() evaluation succeeds, the raw result is converted to []string via the generic convert helper. This error means the CDP-returned value could not be converted to the expected Go string slice — an internal marshalling failure, not a page-level condition.

Solutions

1. Upgrade k6 to the latest patch release so the Go module and injected script versions match: brew upgrade k6 or download the official binary.
2. If it persists, reproduce with a minimal <select> and report it as a bug to the k6-browser GitHub repo including the k6 version.
3. As a workaround, drive the selection manually: click the select, then click the desired <option> element.

Example fix

// workaround while hitting the internal conversion bug
const select = await page.waitForSelector('select#country');
await select.click();
const opt = await select.$('option[value="de"]');
await opt.click();

try {
  await el.selectOption(['de']);
} catch (e) {
  if (String(e).includes('unpacking selected options')) {
    await el.click();
    await (await el.$('option[value="de"]')).click(); // manual fallback
  } else { throw e; }
}

When it happens

Trigger: The injected script returns a non-array or an array containing non-string entries (should not happen with the shipped injected_script.js); a k6/browser version mismatch where the Go wrapper and injected script disagree on the return shape; sobek/CDP serialization returning an unexpected remote object type.

Common situations: Upgrading k6 to a version whose browser module changed the selectOption return contract while a pinned older chromium/browser binary or cached script is in play; essentially only seen with version skew or a bug in the module itself.

Related errors

• getting text content of element: unexpected type %T…
• checking hit target
• checking is in viewport: unexpected type %T
• getting element position
• getting injected script

AI-assisted analysis of grafana/k6@3fcf5388d7 (2026-08-18). Data as JSON: /api/errors/f4a26e01e3346c72. Report an issue: GitHub.

Appendix: source

Thrown at internal/js/modules/k6/browser/common/element_handle.go:1433

	return nil
}

// SelectOption selects the options matching the given values.
func (h *ElementHandle) SelectOption(values []any, opts *ElementHandleBaseOptions) ([]string, error) {
	selectOption := func(apiCtx context.Context, handle *ElementHandle) (any, error) {
		return handle.selectOption(apiCtx, values)
	}
	selectOptionAction := h.newAction(
		[]string{}, selectOption, opts.Force, withRetry, opts.NoWaitAfter, opts.Timeout,
	)
	selectedOptions, err := call(h.ctx, selectOptionAction, opts.Timeout)
	if err != nil {
		return nil, fmt.Errorf("selecting options: %w", err)
	}
	var returnVal []string
	if err := convert(selectedOptions, &returnVal); err != nil {
		return nil, fmt.Errorf("unpacking selected options: %w", err)
	}

	applySlowMo(h.ctx)

	return returnVal, nil
}

// SelectText selects the text of the element.
func (h *ElementHandle) SelectText(opts *ElementHandleBaseOptions) error {
	selectText := func(apiCtx context.Context, handle *ElementHandle) (any, error) {
		return nil, handle.selectText(apiCtx)
	}
	selectTextAction := h.newAction(
		[]string{}, selectText, opts.Force, withRetry, opts.NoWaitAfter, opts.Timeout,
	)
	if _, err := call(h.ctx, selectTextAction, opts.Timeout); err != nil {
		return fmt.Errorf("selecting text: %w", err)
	}

View on GitHub (pinned to 3fcf5388d7)