reactRouterTracingIntegration: transaction name is [object Object] when navigating with object argument

[jbojcic-ai]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues

How do you use Sentry?

Sentry SaaS (sentry.io)

Which SDK are you using?

@sentry/react-router

SDK Version

10.38.0

Framework Version

React Router v7 (framework mode)

Link to Sentry event

N/A

Steps to Reproduce

1. Set up @sentry/react-router with reactRouterTracingIntegration()
2. Navigate using a <Link> (or navigate()) with an object to prop:

   <Link to={{ pathname: `/items/${id}`, search: `redirectTo=${encodeURIComponent(backPath)}` }}>
     View item
   </Link>

3. Observe the transaction name in Sentry shows [object Object]

Expected Result

Transaction name should be the resolved pathname (e.g., /items/:id or /items/123), not [object Object].

Actual Result

Transaction name is [object Object].

Root Cause

In hydratedRouter.js, the patched navigate function uses String(args[0]) to derive the transaction name:

router.navigate = function sentryPatchedNavigate(...args) {
  if (!isClientInstrumentationApiUsed()) {
    maybeCreateNavigationTransaction(String(args[0]) || '<unknown route>', 'url');
  }
  return originalNav(...args);
};

React Router's navigate() accepts multiple argument types:

• string — e.g. "/items/123"
• number — e.g. -1 (go back)
• To object — e.g. { pathname: "/items/123", search: "?foo=bar" }

When called with an object, String({...}) produces "[object Object]".

Suggested Fix

const navTarget = args[0];
const name = typeof navTarget === 'string'
  ? navTarget
  : typeof navTarget === 'number'
    ? `go(${navTarget})`
    : navTarget?.pathname || '<unknown route>';

maybeCreateNavigationTransaction(name, 'url');

[linear]

JS-1833

[jbojcic1]

Can't edit the issue now (I accidentally created it with my agent gh account) but here is the link to Sentry event:

https://make-prisms.sentry.io/issues/6786605134/?alert_rule_id=16176971&alert_type=issue&environment=production&notification_uuid=a4ff8cb4-0b7a-41e0-a368-b857588fb696&project=4509707316690944

[andreiborza]

Hi @jbojcic1, thanks for filing this. We'll take a look.

[nicohrubec]

Thanks for reporting. I was able to reproduce the issue, looking into a fix.