React Native Packager sometimes crashes with WebSocket "ERROR not opened"

Description

When developing an app and reloading the iOS simulator, occasionally the react native packager will crash, and I have to restart it.

Here is the output from my console:

Bundling `index.ios.js`
  No module changed.
Bundling `index.ios.js`
  No module changed.
Bundling `index.ios.js`
  No module changed.
 ERROR  not opened
Error: not opened
    at WebSocket.send (/Users/ndbroadbent/code/myapp/node_modules/ws/lib/WebSocket.js:219:16)
    at Server.packagerServer.setHMRFileChangeListener [as _hmrFileChangeListener] (/Users/ndbroadbent/code/myapp/node_modules/react-native/local-cli/server/util/attachHMRServer.js:149:21)
    at Server.onFileChange (/Users/ndbroadbent/code/myapp/node_modules/react-native/packager/react-packager/src/Server/index.js:406:12)
    at Server.processFileChange (/Users/ndbroadbent/code/myapp/node_modules/react-native/packager/react-packager/src/Server/index.js:236:40)
    at Array.forEach (native)
    at HasteMap.dependencyGraph.getWatcher.on (/Users/ndbroadbent/code/myapp/node_modules/react-native/packager/react-packager/src/Server/index.js:261:40)
    at emitOne (events.js:101:20)
    at HasteMap.emit (events.js:188:7)
    at Timeout.emitChange [as _repeat] (/Users/ndbroadbent/code/myapp/node_modules/jest-haste-map/build/index.js:558:14)
    at Timeout.wrapper [as _onTimeout] (timers.js:425:11)

See http://facebook.github.io/react-native/docs/troubleshooting.html
for common problems and solutions.

Reproduction Steps and Sample Code

This happens when I press CMD+R to reload the iOS simulator, but it only happens once every few hours. Sometimes just once a day.

Solution

Catch the error, and just ignore it instead of crashing.

Workaround

I’ve just been running: while true; do react-native start; done

Additional Information

• React Native version: 0.41.2
• Platform: iOS
• Development Operating System: MacOS
• Dev tools: XCode 8.2.1, iOS 8.4 Simulator.

[a3diti]

i thought the websockets required an error handle but the problem was fixed just by cleaning cache npm start -- --reset-cache

[Tasemu]

+1 driving me crazy