grafana/k6 · error

evaluating script on document: %w

Error message

evaluating script on document: %w

What it means

Page.evaluateOnNewDocument failed to register the script with CDP: the Page.addScriptToEvaluateOnNewDocument command returned an error. This runs when the browser module (or a context's addInitScript path) tries to evaluate a script on every new document, and the page's session could not execute the command.

Source

Thrown at internal/js/modules/k6/browser/common/page.go:637

}

func (p *Page) didClose() {
	p.logger.Debugf("Page:didClose", "sid:%v", p.sessionID())

	p.closedMu.Lock()
	{
		p.closed = true
	}
	p.closedMu.Unlock()
}

func (p *Page) evaluateOnNewDocument(source string) error {
	p.logger.Debugf("Page:evaluateOnNewDocument", "sid:%v", p.sessionID())

	action := page.AddScriptToEvaluateOnNewDocument(source)
	_, err := action.Do(cdp.WithExecutor(p.ctx, p.session))
	if err != nil {
		return fmt.Errorf("evaluating script on document: %w", err)
	}

	return nil
}

func (p *Page) getFrameElement(f *Frame) (handle *ElementHandle, _ error) {
	if f == nil {
		p.logger.Debugf("Page:getFrameElement", "sid:%v frame:nil", p.sessionID())
	} else {
		p.logger.Debugf("Page:getFrameElement", "sid:%v fid:%s furl:%s",
			p.sessionID(), f.ID(), f.URL())
	}

	parent := f.parentFrame
	if parent == nil {
		return nil, errors.New("frame has been detached 1")
	}

View on GitHub (pinned to 93accf6570)

Solutions

1. Call addInitScript before any goto()/newPage-dependent work, ideally right after context creation
2. Await it so failures surface immediately rather than racing navigation
3. If it appears at iteration end only, restructure to finish script setup before teardown starts
4. Check for upstream session failures (DEBUG=k6-browser) when it appears mid-test

Example fix

// before
const page = await browser.newPage();
await page.goto('https://test.k6.io/');
await page.addInitScript ? null : null; // late registration path

// after
const ctx = browser.newContext();
ctx.addInitScript('window.marker = true;'); // registered on live session
const page = await ctx.newPage();
await page.goto('https://test.k6.io/');

if (page.isClosed()) { throw new Error('page closed; init script registration will fail'); }
await ctx.addInitScript('window.marker = 1;');

try {
  await ctx.addInitScript(src);
} catch (e) {
  if (/evaluating script on document/.test(String(e))) return; // session gone; skip
  throw e;
}

When it happens

Trigger: Registering an init/evaluate-on-new-document script while the page session is closed or closing — e.g. addInitScript after page.close() began, or during teardown races at iteration end; or on a dead session after a browser crash.

Common situations: Late addInitScript calls racing context/page close; scripts injecting instrumentation right before navigation completes on a swapped target; running after an earlier crash made the session unusable.

Related errors

• internal error while applying init scripts to page: %w
• attaching new page: %w
• selectHandle.dispose: %w
• attaching worker target ID %v to session ID %v: %w
• disposing element with ID %s: %w

AI-assisted analysis of grafana/k6@93accf6570 (2026-08-15). Data as JSON: /api/errors/f508e2fb0ffd50d2. Report an issue: GitHub.