browsingContextID is not set while using makeFetchTransport from Firefox version 133

[ArulappanS]

Is there an existing issue for this?

• I have checked for existing issues https://github.com/getsentry/sentry-javascript/issues
• I have reviewed the documentation https://docs.sentry.io/
• I am using the latest SDK release https://github.com/getsentry/sentry-javascript/releases

How do you use Sentry?

Sentry Saas (sentry.io)

Which SDK are you using?

@sentry/browser

SDK Version

8.7.0

Framework Version

No response

Link to Sentry event

No response

Reproduction Example/SDK Setup

import {
  BrowserClient,
  makeFetchTransport,
Scope,
} from '@sentry/browser'


let transport = makeFetchTransport;

const defaultConfig = {
  transport,
  …..
}
const browserClient = new BrowserClient({
  ...defaultConfig,
  …..
})

const serviceInstance = new Scope()
serviceInstance.setClient(browserClient)
….
browserClient.init()
…
serviceInstance.captureException(message, {
          captureContext: {
           .....
          }
})

Steps to Reproduce

Send the Sentry request (along with all the required options), using the sample code given.

Observation:
Getting the error in Firefox Parent process Browser Console:
Got a request https://sentry-*****************/&sentry_client=sentry.javascript.browser%2F8.7.0 without a browsingContextID set

Sentry request is shown in the third-party proxy tools, e.g. Fiddler

Figured out that in Firefox 133, fetch API related bug fixes are made:
https://developer.mozilla.org/en-US/docs/Mozilla/Firefox/Releases/133

Workaround:
Tried with a custom fetch transport, the request is listed in the DevTools and no error in the browser console.

function makeCustomFetchTransport(options) {
  function makeRequest(request) {
    const requestOptions = {
      body: request.body,
      method: 'POST',
      referrerPolicy: 'origin',
      headers: options.headers,
      ...options.fetchOptions,
    };

    return fetch(options.url, requestOptions).then(response => ({
        statusCode: response.status,
        headers: {
          'x-sentry-rate-limits': response.headers.get('X-Sentry-Rate-Limits'),
          'retry-after': response.headers.get('Retry-After'),
        },
      }));
  }

  return createTransport(options, makeRequest);
}

It would be helpful if the support is given from Sentry SDK itself.

Expected Result

Sentry request is listed in Firefox DevTools.

Actual Result

Sentry request is not listed in the DevTools, but getting below error in the Firefox Parent process Browser console

Note: Press CMD+Shift+J to open Firefox Parent process Browser console

[Lms24]

Hey @ArulappanS thanks for writing in!

Just to confirm I understand things correctly: you get this error with the default transport and once you remove the keepalive property in your custom transport, the error disappears?

I don't think we'll remove the keepalive flag but we'll look into what specifically is causing this and if we can find a workaround.

[ArulappanS]

@Lms24 Yes, once keepalive property is removed in the custom transport, the error disappears.

[Lms24]

@ArulappanS I tried reproducing this on Firefox 137 with the default transport but everything seems to work correctly. The errors I send successfully show up in Sentry.

Please take a look at my reproduction and let me know what to change so that this is reproducible. Thanks!