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Session replays not routing to dedicated DSN when using makeMultiplexedTransport #20346
Description
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 CDN bundle
SDK Version
10.42.0
Framework Version
No response
Link to Sentry event
No response
Reproduction Example/SDK Setup
<script src="https://browser.sentry-cdn.com/10.42.0/bundle.replay.min.js"
integrity="sha384-sbojwIJFpv9duIzsI9FRm87g7pB15s4QwJS1m1xMSOdV1CF3pwgrPPEu38Em7M9+"
crossorigin="anonymous"></script>
<script src="https://browser.sentry-cdn.com/10.42.0/multiplexedtransport.min.js"
integrity="sha384-p8HeEw7yYcSl/9moL9rH0pJjLSPDCpZz0MHmuysvDyKur6U8PgHLNywONPkNqZyV"
crossorigin="anonymous"></script>
<script>
(function() {
window.Sentry.init({
dsn: "__DEFAULT_DSN__",
replaysSessionSampleRate: 0.1,
replaysOnErrorSampleRate: 1.0,
integrations: [window.Sentry.replayIntegration()],
transport: window.Sentry.makeMultiplexedTransport(
window.Sentry.makeFetchTransport,
function({ getEvent }) {
if (getEvent(["replay_event"])) {
return [{ dsn: "__REPLAY_DSN__" }];
}
return [];
}
),
});
})();
</script>Steps to Reproduce
Steps to Reproduce
- Load bundle.replay.min.js and multiplexedtransport.min.js via CDN script tags
(server-rendered, not dynamically injected) - Initialize Sentry with makeMultiplexedTransport routing replay_event types to a separate
DSN - Trigger a session replay
- Check both Sentry projects
Expected Result
Replay events arrive in the project associated with REPLAY_DSN. Errors and transactions
arrive in the project associated with DEFAULT_DSN.
Actual Result
Replay events are not arriving in the dedicated replay project. They appear to be going to
DEFAULT_DSN instead. window.Sentry.makeMultiplexedTransport is available at runtime (no
warnings), and the matcher function is invoked, but replays still reach the wrong project.
Additional Context
No response
Priority
React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it.
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linear-code commentedon Apr 16, 2026
JS-2199
logaretm commentedon Apr 20, 2026
Thanks for the report, I will check it out and report back.
logaretm commentedon Apr 30, 2026
So I initially thought that #20408 fixed it but it only did for default matchers, since yours is a custom matcher then it wouldn't change anything for you.
I tried to reproduce this in a similar sample and managed to send the replays to a different DSN normally. I put up the repro here:
https://github.com/logaretm/replay-dedicated-dsn
If you can fork it or make changes to reproduce the issue I will be happy to take a look.
getsantry commentedon May 22, 2026
This issue has gone three weeks without activity. In another week, I will close it.
But! If you comment or otherwise update it, I will reset the clock, and if you remove the label
Waiting for: Community, I will leave it alone ... forever!"A weed is but an unloved flower." ― Ella Wheeler Wilcox 🥀
behnammodi commentedon May 22, 2026
@logaretm Thanks for repo, I have gotten some idea from your repo and mine is working now
behnammodi commentedon May 22, 2026
I will close this issue