react native android failed to load JS bundle问题解决办法

来源:  2017-06-18 08:49:10    评论:0点击:


I'm trying to run AwesomeProject on my Nexus5 (android 5.1.1).

I'm able to build the project and install it on the device. But when I run it, I got a red screen saying

    Unable to download JS bundle. Did you forget to start the development server or connect your device?

In react native iOS, I can choose to load jsbundle offline. How can I do the same thing for Android? (Or at least, where can I configure the server address?)
To run with local server, run the following commands under your react-native project root directory

    react-native start > /dev/null 2>&1 &
    adb reverse tcp:8081 tcp:8081

please take a look at dsissitka's answer for more details.
To run without a server, bundle the jsfile into the apk by running:

    create an assets folder under android/app/src/main
    curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"

please take a look at kzzzf's answer for more details.


To bundle JS file into your apk while having your server running (react-native start) download bundle into assets directory of your app:

curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"

With the next release (0.12) we'll fix react-native bundle command to work with android projects as expected.


The following made it work for me on Ubuntu 14.04:

cd (App Dir)
react-native start > /dev/null 2>&1 &
adb reverse tcp:8081 tcp:8081

Update: See

Update 2: @scgough We got this error because React Native (RN) was unable to fetch JavaScript from the dev server running on our workstations. You can see why this happens here:


If your RN app detects that you're using Genymotion or the emulator it tries to fetch the JavaScript from GENYMOTION_LOCALHOST ( or EMULATOR_LOCALHOST ( Otherwise it presumes that you're using a device and it tries to fetch the JavaScript from DEVICE_LOCALHOST (localhost). The problem is that the dev server runs on your workstation's localhost, not the device's, so in order to get it to work you need to either:


Ok, I think I've figured what the issue is here. It was to do with the version of watchman I was running.

In a new shell, run brew update then: brew unlink watchman then: brew install watchman

now, you can run react-native start from your project folder

I leave this shell open, create a new shell window and run: react-native run-android from my project folder. All is right with the world.

ps. I was originally on version 3.2 of watchman. This upgraded me to 3.7.

pps. I'm new to this so that might not be the swiftest route to the solution but it has worked for me.


You might find that if you deploy your app to your Android device rather than an emulater you get a red screen of death with an error saying Unable to load JS Bundle. You need to set the debug server for your device to be your computer running react...either its name OR IP address.

  1. Press the device Menu button
  2. Select Dev Settings
  3. Select Debug server host for device
  4. Type in your machine's IP and Reload JS plus the react port e.g.

More info: http://facebook.github.io/react-native/docs/running-on-device-android.html


From your project directory, run

react-native start

It outputs the following:

$ react-native start
   Running packager on port 8081.                                             
   Keep this packager running while developing on any JS projects. Feel       
   free to close this tab and run your own packager instance if you           
   https://github.com/facebook/react-native                                  │ 
Looking for JS files in

React packager ready.

[11:30:10 PM] <START> Building Dependency Graph
[11:30:10 PM] <START> Crawling File System
[11:30:16 PM] <END>   Crawling File System (5869ms)
[11:30:16 PM] <START> Building in-memory fs for JavaScript
[11:30:17 PM] <END>   Building in-memory fs for JavaScript (852ms)
[11:30:17 PM] <START> Building in-memory fs for Assets
[11:30:17 PM] <END>   Building in-memory fs for Assets (838ms)
[11:30:17 PM] <START> Building Haste Map
[11:30:18 PM] <START> Building (deprecated) Asset Map
[11:30:18 PM] <END>   Building (deprecated) Asset Map (220ms)
[11:30:18 PM] <END>   Building Haste Map (759ms)
[11:30:18 PM] <END>   Building Dependency Graph (8319ms)


An easy solution that works for me with Ubuntu 14.04.

react-native run-android

The emulator (already launched) will return: Unable to download JS Bundle; start again the JS server:

react-native start

Hit Reload JS on the emulator. It worked for me. Hope it will help


This error can easily resolved by following steps:

    //run the command at /android sdk / platforms-tool folder
        adb reverse tcp:8081 tcp:8081

    //now come to root folder of your app
    1. npm start
    2. create 'assets' folder inside rootApp/android/app/src/main/
    3. curl "http://localhost:8081/index.android.bundle?platform=android" -o "android/app/src/main/assets/index.android.bundle"
    4. make sure anyone physical or virtual device attached is running.
    5. react-native run-android


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