React native - connection has no connection handler error meaning?

failed : error 0:61 [61]
react-native websocket connection refused
nw_socket_handle_socket_event connection reset by peer
react devtools react native
nw_socket_handle_socket_event socket so_error 54 connection reset by peer
react-devtools port

I created a new react project and when I run it on iOS from xcode, the console gives me this:

2017-05-19 23:25:34.119 [info][tid:main][RCTBatchedBridge.m:77] Initializing <RCTBatchedBridge: 0x6100001a6c80> (parent: <RCTBridge: 0x6100000c46e0>, executor: RCTJSCExecutor)
2017-05-19 23:25:51.287 [info][tid:main][RCTRootView.m:295] Running application test ({
    initialProps =     {
    rootTag = 1;
2017-05-19 23:25:51.289 [info][tid:com.facebook.react.JavaScript] Running application "test" with appParams: {"rootTag":1,"initialProps":{}}. __DEV__ === true, development-level warning are ON, performance optimizations are OFF
2017-05-19 23:25:51.299771-0400 test[21948:1121429] [] nw_connection_get_connected_socket_block_invoke 3 Connection has no connected handler
2017-05-19 23:25:53.335282-0400 test[21948:1121426] [] nw_connection_get_connected_socket_block_invoke 4 Connection has no connected handler
2017-05-19 23:25:55.349190-0400 test[21948:1120112] [] nw_connection_get_connected_socket_block_invoke 5 Connection has no connected handler

What do 2017-05-19 23:25:51.299771-0400 test[21948:1121429] [] nw_connection_get_connected_socket_block_invoke 3 Connection has no connected handler these lines mean and how to I resolve the issue?

I first noticed this when I tried to use fetch in my application and found it did not work. I found these messages in the console and later discovered these messages are happening with all my applications so I assume that means it is a config issue on my part?

I created a new test program to test what was causing this and found it happens on a brand new project. Below is my code is that generated the log output above:

 * Sample React Native App
 * @flow

import React, { Component } from 'react';
import {
} from 'react-native';

export default class test extends Component {
  render() {
    return (
      <View style={styles.container}>
        <Text style={styles.welcome}>
          Welcome to React Native!
        <Text style={styles.instructions}>
          To get started, edit index.ios.js
        <Text style={styles.instructions}>
          Press Cmd+R to reload,{'\n'}
          Cmd+D or shake for dev menu

const styles = StyleSheet.create({
  container: {
    flex: 1,
    justifyContent: 'center',
    alignItems: 'center',
    backgroundColor: '#F5FCFF',
  welcome: {
    fontSize: 20,
    textAlign: 'center',
    margin: 10,
  instructions: {
    textAlign: 'center',
    color: '#333333',
    marginBottom: 5,

AppRegistry.registerComponent('test', () => test);

Try Below process

Xcode menu -> Product -> Edit Scheme...

Environment Variables -> Add -> Name: "OS_ACTIVITY_MODE", Value:"disable"

Run your app again

8 Steps to Get Rid Of Error “nw_connection_get_connected_socket , This steps for React Native… Rid Of Error “​nw_connection_get_connected_socket Connection has no connected handler TCP Conn Failed : error 0:61 [61]”. As for the native part you either handle it yourself (if you have developed sth there) or you can use ‘react-native-exception-handler’ which can be useful for many cases.

I figured out the solution:

To turn off Verbose for OS Activity Mode

  1. From the xcode menu, Project -> Scheme -> Edit Scheme.
  2. Then select Run on the left and then select Arguments tab on the right.
  3. In Environment Variables add the name OS_ACTIVITY_MODE and value as disable.

Or see picture below.

Note: credit for image goes to Ramkrishna Sharma

nw_connection_get_connected_socket connection has no , connected handler. “__nw_connection_get_connected_socket_block_invoke Connection has no connected handler” error on iOS 10. 41. iOS · React Native​  (the same for the other methods). However, no matter what I try I cannot manage to make an outbound call (microphone permissions have been enabled). As suggested I run the initWithToken on component mount and add the few listeners.

This error is most likely from the websocket that is built into react-native to connect to the react-devtools. If you aren't running react-devtools while debugging, then you will get this error, and it also pumps a bunch of messages across the bridge complaining about not being able to open the websocket (you will only see those errors if you are using something like rn-snoopy).

The error will stop as soon as you install and open react-devtools. See these instructions for how to do it:

Xcode 10 runtime warning on fresh install, Description While running the boilerplate react native app, I receive the runtime error: In the mean time you'll see websocket connection errors, as the bundler is not ready yet. I mean, what exactly is it trying to connect to? React native-connection n'a pas d'erreur de gestionnaire de connexion? j'ai créé un nouveau projet react et quand je l'exécute sur iOS à partir de xcode, la console me donne ceci:

"__nw_connection_get_connected_socket_block_invoke , Ah. OK - I think the issue is that react-native is integrated into my project, which nw_connection_get_connected_socket 42 Connection has no connected handler #1 Connection has no connected handler" error on iOS 10  react-native-exception-handler A react native module that lets you to register a global error handler that can capture fatal/non fatal uncaught exceptions. The module helps prevent abrupt crashing of RN Apps without a graceful message to the user. In the current scenario:

React+native+connection+has+no+connection+handler+error+ , Sometimes an app needs to access a platform API and React Native doesn't have a React Native will not expose any methods of CalendarManager to JavaScript the first parameter an error object (usually null when there is no error) and the Enums that are defined via NS_ENUM cannot be used as method arguments  OK - I think the issue is that react-native is integrated into my project, which was originally ONLY a native obj-c project. React was integrated in afterwards (using instructions here ). So my project doesn't have a Libraries folder that contains each of the individual xcodeproj files. The files are in the project,

Native Modules · React Native, isConnected (boolean) -- if there is an active network connection. Note that this does not mean that internet is reachable. This field is false if the type is either  Teams. Q&A for Work. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information.

Network, Confirm that react-native link has added the Realm module; if it has not, link manually to replace the definition of class <project-name> with the following in App.js : here }) .catch(error => { // Handle the error here if something went wrong });. Detect if the current active connection is metered or not. A network is classified as metered when the user is sensitive to heavy data usage on that connection due to monetary costs, data limitations or battery/performance issues. NetInfo.isConnectionExpensive() .then(isConnectionExpensive => { console.log('Connection is

Create reactive mobile apps in a fraction of the time, Most of the times the problem is that you have another react-native start (i.e. React Native Packager) server running either on another terminal or another tab of TMUX (if you are using TMUX). You need to find that process and close it, so after running react-native run-ios for instance,

  • Thank you! That worked, would you mind explaining why that worked?
  • This is not a solution, this is hiding errors. A real fix has not been found yet:
  • Actually, I found that my iPhone app, which has been working fine for years, suddenly stopped being able to talk to my web services. Adding this Environment Variable, and rebuilding/deploying the app fixed the error.... So, for me, this did more than just hiding a few error messages.
  • This will hide your NSLog's when using a real device. Change the 'disable' value to an empty string when testing on a real device. See
  • I still got the error. Even though I started react-devtools
  • I'm running React Native on an iPad. I can't see how to tell it to connect to the react-devtools on my dev machine - ideas?
  • So you're implying the react-devtools is somehow required for running react native? That's odd...