3.4-rc.3 Release Candidate, Faster Builds, Smaller Bundles and Modern Setups with the Rspack integration ⚡

dupontbertrand · April 10, 2026, 8:43am

@schlaegerz Can you try with that ? fix: disable HMR proxy in test mode by dupontbertrand · Pull Request #14329 · meteor/meteor · GitHub

nachocodoner · April 13, 2026, 10:55am

I also encountered that Meteor HMR also triggers these errors when I was testing the meteor test in the client side on the apps.

I will include the next fix for it along with @dupontbertrand.

github.com/meteor/meteor

Disable HMR WebSocket connection during test modes to prevent errors

meteor:release-3.4.1 ← meteor:hmr-test-disable-tool

opened 10:52AM - 13 Apr 26 UTC

nachocodoner

+5 -1

Continues: https://github.com/meteor/meteor/pull/14329 When I was testing tes…t mode to verify https://github.com/meteor/meteor/pull/14329 , I still saw error logs being triggered, but instead of coming from Rspack mode, they were coming from Meteor's HMR package. Running `meteor test` / `meteor test --full-app` against an app with `hot-module-replacement` spams the browser console with: ``` WebSocket connection to 'ws://localhost:3000/__meteor__hmr__/websocket' failed ``` HMR is already disabled at compile time in test runs (`compiler-plugin.js` gates `hmrAvailable` on `buildMode === 'development'`), so no change sets ever flow, the client's connection attempts are dead wiring that also race with SockJS for the upgrade path, the same class of bug fixed for Rspack in [#14329](https://github.com/meteor/meteor/pull/14329). This PR solves the fix and guard the `enabled` flag in `packages/hot-module-replacement/client.js` with `!Meteor.isTest && !Meteor.isAppTest`. Dev mode and Cordova unaffected.