react-native can't - Android failed to load JS bundle




metro packaged (18)

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?)

Update

To run with local server, run the following commands under your react-native project root directory

  1. react-native start > /dev/null 2>&1 &
  2. 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:

  1. create an assets folder under android/app/src/main
  2. 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.


Answers

I don't have enough reputation to comment, but this is referring to dsissitka's answer. It works on Windows 10 as well.

To reiterate, the commands are:

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

You can follow the instruction mentioned on the official page to fix this issue. This issue occur on real device because the JS bundle is located on your development system and the app inside your real device is not aware of it's location.


I was getting this on Linux after stopping down the react-native run-android process. Seems the node server is still running so the next time you run it, it won't run properly and your app can't connect.

The fix here is to kill the node process which is running in an Xterm which you can kill by ctrl-cing that window (easier) or you can find it using lsof -n -i4TCP:8081 then kill -9 PID.

Then run react-native run-android again.


After trying out a combination of the answers here, this is what is working for me.

I'm using Genymotion as my emulator.

1 Start up Genymotion emulator.

2 From a terminal

cd AwesomeProject
react-native run-android # it loads in genymotion and fails with bundle error
react-native start > /dev/null 2>&1 & # from dsissitka
adb reverse tcp:8081 tcp:8081 # from dsissitka

3 Reload from emulator.

It loads!

I can now begin developing.


I am using Ubuntu and Android only, and I was unable to get it running. I found a really simple solution which is to update your package.json file, changing this lines:

"scripts": {
    "start": "node node_modules/react-native/local-cli/cli.js start"
  },

to

"scripts": {
    "start": "adb reverse tcp:8081 tcp:8081 && node node_modules/react-native/local-cli/cli.js start"
  },

And then you run the server by typing

npm run start

This ensures the android device looks for the node server on your computer instead of locally on the phone.


Here are the simple steps to run your app on android(release):

1. Go to your application root.

2. Run this command.

react-native bundle --platform android --dev false --entry-file index.android.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res

All your files are copied.

3. Create signed APK.

Open android studio.

Build > Generate Signed APK > [Fill required details, keystroke has to be generated before this step]

Your APK should be generated without any errors. Install on your device and this should work without any issues.

You can also connect your device and directly hit Run icon on android studio for testing.


Generating Keystroke:

  1. Goto C:\Program Files\Java\jdkx.x.x_x\bin

  2. Run

keytool -genkey -v -keystore d:\my_private_key.keystore -alias my-key-alias -keyalg RSA -keysize 2048 -validity 10000

It will probably ask you to fill in some details. Do it and your have your keystroke file(my_private_key.keystore) which can be used to sign your apk.


Delete the App from your phone! I tried several steps, but that did it eventually.

  1. If you tried to run your app before but failed, delete it from your android device.
  2. Run $ react-native run-android
  3. Open the React Rage Shake Menu from within your app on your android device, go to Dev Settings and then to Debug server host & port for device. There enter your server IP (IP of your computer) and host 8081, e.g. 192.168.50.35:8081. On a mac you can find the IP of your computer at System Preferences -> Network -> Advanced... -> TCP/IP -> IPv4 Address.
  4. Open the Rage Shake Menu again and click Reload JS.

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


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.

* MORE INFO FOR RUNNING/DEBUGGING ON A DEVICE *

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. 192.168.1.10:8081

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


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:

https://github.com/facebook/react-native/blob/42eb5464fd8a65ed84b799de5d4dc225349449be/ReactAndroid/src/main/java/com/facebook/react/devsupport/DevServerHelper.java#L116-L137

If your RN app detects that you're using Genymotion or the emulator it tries to fetch the JavaScript from GENYMOTION_LOCALHOST (10.0.3.2) or EMULATOR_LOCALHOST (10.0.2.2). 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:


An update

Now on windows no need to run react-native start. The packager will run automatically.


Check your wifi connection.

Another possibility could be you are either not connected to wifi, connected to the wrong network, or the ip address is wrong in your dev settings. For some reason, my android disconnected from the wifi and I started to get this error, unknowingly.


The initial question was about reloading the application in a phyisical device.

When you're debugging the application in a physical device (ie via adb), you can reload the JS bundle by clicking on the top left "action" button of your device. This will open the option menu (Reload, Debug JS remotely...).

Hope this helps.


Running npm start from react-native directory worked out for me.


One important thing to check that no one has mentioned so far: Check your local firewall, make sure it's turned OFF.

See my response here: https://.com/a/41400708/1459275



Try Genymotion for Android Studio. Blazing fast! Just needs one time installation. No more AVD pain.







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