react-native run-android command terminates by leaving a message in android simulator. The message is as follows:

Unable to load script.Make sure you are either running a Metro server or that your bundle '' is packaged correctly for release.

What am I doing wrong?

Solution 1

You haven't started the bundler yet. Run npm start or react-native start in the root directory of your project before react-native run-android.

Solution 2

These steps really help me:

Step 1: Create a directory in android/app/src/main/assets

Linux command: mkdir android/app/src/main/assets

Step 2: Rename (in root directory) to index.js (Maybe there is an index.js file in which case you do not need to rename it) then run the following command:

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

Step 3: Build your APK: react-native run-android

Please use index.js in latest version.

Enjoy :)

Solution 3

If you have everything correctly configured then try this:

adb reverse tcp:8081 tcp:8081


When the RN packager is running, there is an active web server accessible in your browser at It's from this server that the JS bundle for your application is served and refreshed as you make changes. Without the reverse proxy, your phone wouldn't be able to connect to that address.

All credits to Swingline0 .

Solution 4

For me this error was caused by an upgrade of react-native

Starting with Android 9.0 (API level 28), cleartext support is disabled by default.

If you check out the upgrade diff you need to create a debug manifest android/app/src/debug/AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android=""
    <uses-permission android:name="android.permission.SYSTEM_ALERT_WINDOW"/>
    <application android:usesCleartextTraffic="true" tools:targetApi="28" tools:ignore="GoogleAppIndexingWarning" />

See for more info:

Solution 5

A similar issue happened with me.
Apparently Mcafee blocks 8081 port. Took me hours to figure this out.

Try running:

react-native run-android --port=1234

When app shows up with an error on emulator, get into dev settings (Ctrl+M).

Change the "Debug server host and port for device" to "localhost:1234".

Close the app and start it from the app drawer.

Solution 6

You can try the following:

Add this line on your AndroidManifest.xml


EDIT: Be careful, it must be false on production for the security of your app

Solution 7

just add three splash in : node_modules\metro-config\src\defaults\blacklist.js

replace this part:

var sharedBlacklist = [

Solution 8

First do steps 4 and 5 then you can run your project. If you do not get the result (with steps 4 and 5) do the following steps

1- Try to downgrade your Node version (current version is 12.13.1)

  choco uninstall nodejs
  choco install nodejs --version 12.8

2- Add the path of npm module (C:\Users\your user name\AppData\Roaming\npm) to system variables instead of user variables

3- Install react native globally by using command

  npm install -g react-native-cli

4- Go to the root of your project directory and run the following command :

  react-native start

5- Open another terminal in the root of your project and run the following command :

   react-native run-android 


You are using Genymotion ? If yes, do the following step :

After above step if you get the following error ?

error Failed to launch emulator. Reason: No emulators found as an output of `emulator -list-avds`.

Open your genymotion and go to :

genymotion menu -> Settings -> ADB -> Then select use custom android sdk tools (click on browse to find sdk location)

Finally , run you project again ..

Solution 9

[Quick Answer]

After try to solve this problem in my workspace I found a solution.

This error is because there are a problem with Metro using some combinations of NPM and Node version.

You have 2 alternatives:

  • Alternative 1: Try to update or downgrade npm and node version.
  • Alternative 2: Go to this file: \node_modules\metro-config\src\defaults\blacklist.js and change this code:

    var sharedBlacklist = [

    and change to this:

    var sharedBlacklist = [

    Please note that if you run an npm install or a yarn install you need to change the code again.

Solution 10

This worked for me after trying several ways.

In the file node_modules\metro-config\src\defaults\blacklist.js

Replace :

var sharedBlacklist = [

with :

var sharedBlacklist = [

hope this helps.

Solution 11

I've encountered the same issue while following the React Native tutorial (developing on Linux and targeting Android).

This issue helped me resolve the problem in following steps. Run following commands in the below sequence:

  1. (in project directory) mkdir android/app/src/main/assets
  2. react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/ --assets-dest android/app/src/main/res
  3. react-native run-android

You can automate the above steps by placing them in scripts part of package.json like this:

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

Then you can just execute npm run android-linux from your command line every time.

Solution 12

In my case, the emulator's Wifi and Mobile Data was off.

Solution 13

Starting with Android 9.0 (API level 28), cleartext support is disabled by default.

This is what you need to do to get rid of this problem if you do normal run commands properly

  1. npm install
  2. react-native start
  3. react-native run-android

And modify your android manifest file like this.

    android:usesCleartextTraffic="true" // add this line with TRUE Value.

Solution 14

If you are on linux open the terminal from the App root directory and run

npm start

then open another terminal window and run:

react-native run-android

Solution 15

Like most of us I assume you are running on VSCODE. In my case, I ran

npx react-native start

from a seperate terminal

Now run npx react-native run-android from your terminal in VSCODE

Solution 16

My solution to this is as below:

Start Metro server

$ react-native start

Start Android

$ react-native run-android

If see errors saying "port 8081 already in use", then you can kill that process and rerun

$ react-native start

See React Native Troubleshooting Page .

Solution 17

After hours searching for a answer. The solution was to make a downgrade node to version 12.4.

In my case I realize that the error just occurs in version react native 0.60 with node version 12.6.

Solution 18

Hey guys a combination of 2 awnsers solved my problem. It was port related.

adb reverse tcp:8088 tcp:8088
react-native run-android --port=8088

By doing this, the app loaded fine of my phone connected by USB. I think my AV or Vagrant or something elses in my PC was using that port.

You can change 8088 to something else if needed.


Solution 19

I just want to add a non-obvious possibility not covered here. I am using @react-native-community/netinfo for detecting network changes, primarily network state. To test network-off state, the WIFI switch (on the emulator) needs to be switched off. This also effectively cuts off the bridge between the emulator and the debug environment. I had not re-enabled WIFI after my tests since i was away from the computer and promptly forgot about it when i got back.

There is a possibility that this could be the case for somebody else as well and worth checking before taking any other drastic steps.

Solution 20

I have also faced this issue. I resolved this following step.

Check android sdk path in Environment Veritable.

Add ANDROID_HOME = C:\Users\user_name\AppData\Local\Android\Sdk in System Variable
and C:\Users\user_name\AppData\Local\Android\Sdk\platform-tools path in System Variable

replace sharedBlacklist as below code segment,

var sharedBlacklist = [

in node_modules/metro-config/src/default/blacklist.js

Then run npx react-native run-android --port 9001

Happy Coding..!

Solution 21

Apparently, none of the answers fixed the issue for me. I was able to run the react-native app on emulator but the same code (even when the Server was running), gave me this error when running the app on the device.

I was able to resolve it by executing the following command in the terminal:

adb reverse tcp:8081 tcp:8081

Solution 22

I was having the same trouble, the problem for me was that adb was not in the right environment path, the error is telling you metro port, while you're in the adb, ports are killed and restarted.

Add Enviroment Variable (ADB)

  1. Open environment variables
  2. Select from the second frame PATH variable and click edit option below
  3. Click on add option
  4. Submit the sdk platform tools path C:\Users\ My User \AppData\Local\Android\Sdk\platform-tools

Note: Or depending where is located adb.exe in your machine

  1. Save changes

Run android build again

$ react-native run-android


$ react-native start

$ react-native run-android

Solution 23

In my case, I've set a proxy in my emulator. It works back to normal after I removing that proxy.

Solution 24

I'm sure it some combination of the other things mentioned here like allowing clear text, which I enabled for localhost. But this was the final piece in the puzzle.

project.ext.react = [
    entryFile: "index.js",


    bundleAssetName: "",
    bundleInDebug: true,
    bundleInRelease: true

RN: 0.61.3

Solution 25

Here how I solved this issue without touching the build:

1- Closed the Virtual Device

2- Tested on Physical Device --(it works)

3- Created new Virtual Device with API 30 Android 10+

4- Try again on newly created Virtual Device, and all work like a charm.

Solution 26

In my case I was trying to run the application on the emulator. But, I was getting this

This IP was accessible from emulator chrome browser. The issue is that this IP is not whitelisted in Android Network Security Settings. So, whatever IP Address you are seeing here add that in below settings and you are good to go.


+               android:usesCleartextTraffic="true"   <- Add this line

    <domain-config cleartextTrafficPermitted="true">
        <domain includeSubdomains="true">localhost</domain>
        <domain includeSubdomains="true"></domain>
        <domain includeSubdomains="true"></domain>
        <domain includeSubdomains="true"></domain>

Just replace <domain includeSubdomains="true"></domain> with the IP you are shown in the error from react-native.

Solution 27

I experienced this just because my Wifi was mistakenly turned off on my emulator.i turned it back on and it started working fine. Hope it's helpful to someone

Solution 28

For me this problem started with upgrading react-native. The upgrade was necessary to add 64-bit support.

Node: 10.15.0
npm: 6.9.0
Watchman: 4.9.0
Xcode: Not Found
Android Studio: 3.4 AI-183.6156.11.34.5692245

Packages: (wanted => installed)
react: 16.0.0-alpha.12 => 16.0.0-alpha.12
react-native: ~0.55.2 => 0.55.4
react-native-cli: 2.0.1

React Native Environment Info:
Node: 10.15.0
npm: 6.9.0
Watchman: 4.9.0
Android SDK:
API Levels: 23, 26, 27, 28
Build Tools: 27.0.3, 28.0.3
System Images: android-28 | Google APIs Intel x86 Atom
Android Studio: 3.4 AI-183.6156.11.34.5692245
Xcode: /undefined - /usr/bin/xcodebuild
react: ^16.8.6 => 16.9.0 
react-native: 0.59.9 => 0.59.9 
create-react-native-app: 2.0.2
react-native-cli: 2.0.1

Also, One important change that I made for the upgrade was in ../android/build/build.gradle

android {
    defaultConfig {
        targetSdkVersion 28

I had to change the targetSdkVersion from 27 to 28 following warning when I tried to upload the build(.apk) to goole play console. Little did i realise that this was the root cause of the above error for me. Immediatly answers by @tom and @tinmarfrutos made absolute sense.

I solved the problem by adding android:usesCleartextTraffic="true" to my android/app/src/debug/AndroidManifest.xml

Solution 29

possibility of this error is also the wrong path,check once

 export ANDROID_HOME=/Users/microrentindia/Library/Android/sdk/
 export PATH=$PATH:$ANDROID_HOME/tools:$ANDROID_HOME/platform-tools

Solution 30

The solution that worked for me is the following:

var sharedBlacklist = [