App crash on opening it on android device. Build successfully but raising an error "Failed to connect to development server".
There can be multiple issues with this.
Check that your node package mananger is running close it, connect
your mobile and run the following command.
adb reverse tcp:8081 tcp:8081
npx react-native start
it my solve your problem.
second
if you want wireless debugging, shake your cellphone it will open the debug menu click on the setting , find your ip address witht he command ipconfig/all and then click on Debug server host & port for device enter your IP like this xxx.xxx.xx.xx:8081 and press R from your development server.
Hope this solve your porblem
I've created a new React Native project -- using react-native init myproject and now trying to debug it in Visual Studio Code. When I click Debug Android, I get an error in Android emulator telling me that it can't connect to remote debugger -- see below:
In the Debug screen, I added the necessary config settings into launch.json -- see below.
What else do I need to do to be able to debug my React Native app in VS Code?
I solved this using adb reverse tcp:8081 tcp:8081 and then reload or rebuild emulator by using react-native run android
Try to:
1. Disable Debug Android
2. run adb reverse tcp:8081 tcp:8081
3. Close Chrome Debug remote
4. Stop and run again react-native start --reset-cache, reload your app and wait app start and then try again Debug Android.
It works always with me
I execute the project with react-native run-android and in another terminal, i do:
npm run react-devtools
and it opens the new window of electron that says:
The react native app it will open in a few seconds...
but nothing happens.
I put in the simulator toggle inspector with Ctrl + m and i can see in networks that it makes a request to http://localhost:8097 and the result is it fails to connect and keeps trying with the same result.
The window of electron that is open it says that it wait connections to the port 8097 so i can see is trying to connect but with no results!
You need to run this command in a new terminal adb reverse tcp:8097 tcp:8097
react-devtools v4 is incompatible with react-native
try version 3 instead of version 4:
npm install -d -g react-devtools#3.x, it's worked for me.
The answer by #Unemployed3494 didn't work for me. Instead I killed all running processes belonging to my Mac OS user with this command:
pkill -u username
After doing so, react devtools connected as expected to the simulator.
I'm using React.JS and when I do react-native run-android (with my device plugged in) I see a blank page. When I shake the device and select Debug JS Remotely from the option list I see the following screen.
FYI:
OS: Ubuntu 16.04
Node version is: v4.6.2
java version "1.8.0_111"
react": "15.4.1
react-native": "0.38.0
In my case the issue was that the emulator was making a request to:
http://10.0.2.2:8081/debugger-ui
instead of:
http://localhost:8081/debugger-ui and the request was failing.
To solve the issue: Before enabling remote debugging on your emulator, open http://localhost:8081/debugger-ui in chrome. Then enable remote debugging and go back to the chrome page where you should see your console logs.
Solved the issue following:
Press Cmd + M on emulator screen
Go to Dev settings > Debug server host & port for device
Set localhost:8081
Rerun the android app: react-native run-android
Debugger is connected now!
I solved it doing adb reverse tcp:8081 tcp:8081 and then reload on my phone.
In my case, selecting Debug JS Remotely launched Chrome, but did not connect with the android device. Normally, the new Chrome tab/window would have the debugging URL pre-populated in the address bar, but in this case the address bar was blank. After the timeout period, the "Unable to connect with remote debugger" error message was displayed. I fixed this with the following procedure:
Run adb reverse tcp:8081 tcp:8081
Paste http://localhost:8081/debugger-ui into the address field of my Chrome browser. You should see the normal debugging screen but your app will still not be connected.
That should fix the problem. If not, you may need to take the following additional steps:
Close and uninstall the app from your Android device
Reinstall the app with react-native run-android
Enable remote debugging on your app.
Your app should now be connected to the debugger.
I had a similar issue that led me to this question. In my browser debugger I was getting this error message:
Access to fetch at 'http://localhost:8081/index.delta?platform=android&dev=true&minify=false' from origin 'http://127.0.0.1:8081' has been blocked by CORS policy: No 'Access-Control-Allow-Origin' header is present on the requested resource. If an opaque response serves your needs, set the request's mode to 'no-cors' to fetch the resource with CORS disabled.
It took me awhile to realize I was using 127.0.0.1:8081 instead of localhost:8081 for my debugger.
To fix it, I simply had to change Chrome from:
http://127.0.0.1:8081/debugger-ui/
to
http://localhost:8081/debugger-ui/
My case is that when I tap enable remote JS debugging, it will launch chrome, but can not connect to it.
I have tried to run:
adb reverse tcp:8081 tcp:8081
, did but not work.
I uninstalled my chrome totally and install a new one. And it works.
The other answers here were missing one crucial step for me. In AndroidManifest.xml I needed to add usesCleartextTraffic:
<application
...
android:usesCleartextTraffic="true">
You probably don't want to keep this in the production release of your app though, unless you want to support insecure http requests.
After I added this to my AndroidManifest.xml, then I followed Tom Aranda's answer, and the emulator was finally able to connect to the debugger.
Make sure that the node server to provide the bundle is running in the background. To run start the server use npm start or react-native start and keep the tab open during development
react-native start --reset-cache in one tab and react-native run-android in another
adb reverse tcp:8081 tcp:8081 ( so you could add it to your scripts and just run yarn run adb-reverse)
If you're using android, Instead of shake your phone a great tip is run adb commands.
So you can run:
adb shell input keyevent 82 (menu option )
adb shell input keyevent 46 46 ( reload )
I did #sajib s answer and used this script to redirect ports:
#!/usr/bin/env bash
# packager
adb reverse tcp:8081 tcp:8081
adb -d reverse tcp:8081 tcp:8081
adb -e reverse tcp:8081 tcp:8081
echo "🚧 React Native Packager Redirected 🚧"
uninstall your application, then run react-native run-android. then click debugging end in chrome replace http://localhost:8081/debugger-ui/, end run react-native run-android. if you still haven't succeeded try again
Inculding all impressive answers the expert developers specially Ribamar Santos provided, if you didn't get it working, you must check something more tricky!
Something like Airplane mode of your (emulated) phone! Or your network status of Emulator (Data status and Voice status on Cellular tab of Emulator configuration) that might be manipulated to don't express network! for some emulation needs!
I've overcome to this problem by this trick! It was a bit breathtaking debug to find this hole!
in my case it also need to install it's npm package
so
npm install react-native-debugger -g
Try adding this
package.json
devDependencies: {
//...
"#react-native-community/cli-debugger-ui": "4.7.0"
}
Terminate everything.
npm install
npx react-native start
npx react-native run-android
Reference: https://github.com/react-native-community/cli/issues/1081#issuecomment-614223917
Trouble shooting React native with React Cli and Typescript/js (Android Emulator)
Check if 'android/src/mai/assets/index.android.bundle' is available. If no Create index.android.bundle file in 'android/src/main/assets'
If above path not available then create the path then file
3.Run for bundling : react-native bundle --platform android --dev false --entry-file index.js --bundle-output android/app/src/main/assets/index.android.bundle --assets-dest android/app/src/main/res
4.a. By default development server runs on 8081 port. Run 'react-native start' then on browser check if 'http://localhost:8081' and 'http://yourIP:8081' works. If yes then
Open application in Android Emulator (react-native run-android)
Click Ctrl + M
Select Settings
Select Debug Server Host and Port For Device
Add 'YourIPAddress:8081' e.g. 10.0.2.2:8081
4.b If http://localhost:8081 not working then run react-native port=8088(or any port)once successfully executed. Check on browser http://localhost:8088 and http://yourIP:8088 works. Yes then Open application in Android Emulator (react-native run-android)
Click 'Ctrl + M'
Select Settings-
Select Debug Server Host and Port For Device-
Add 'YourIPAddress:8081' e.g. 10.0.2.2:8088
YourIPAddress : Open command promt -> write 'ipconfig' -> copy IPv4 address
As for my own case , i was using the expo go and my android phone for my emulator and it was giving me this error.
so what i did was to clear the expo go app cache & data on my android device. it was working just fine
TL;DR:
If you created the app with expo cli with some native code or libraries not supported by expo, try this command in case the other solutions do not work.
npx expo run:android
Docs
My scenario:
I tried to run one of my old expo applications by building the app from Android studio and faced this issue. The other solutions mentioned didn't work. When I tried to use Expo Go to scan the QR, I got to know the error. Since I had used react-native-mmkv, I couldn't use expo-cli, I had to eject. So I ran npx expo run:android and everything started working fine.
The solution is to clear the expo go application data to solve the problem. Ref to: How to disable Remote JS Debugging in React-Native
I have installed the development environment for react native on Windows 7 using the instructions here.
I have installed the following packages:
Python 2.7
node 4.2.4
npm 2.14.12
react-native-cli 0.1.10
react-native 0.18.0-rc
Android SDK
I can generate a skeleton project using the command react-native init Test.
However, when I execute the command react-native run-android, the following error occurs: Unable to install path\to\app-debug.apk.
The device, a Samsung Galuxy running Android 5.0.1, is connected to my PC and USB debugging on the phone has been enabled. When I type adb devices the phone appears in the list.
I can download the apk to the phone manually using the command adb install. However, when I run the app, a red screen appears with the error "Unable to download js bundle." This error persists even after I do the following:
Start the local development server using react-native start
Executing the command: adb reverse tcp:8081 tcp:8081
On the phone, setting the debug server host and port to localhost:8081
Update: I have solved one problem by downloading gradle to version 1.2.3 as described here. However, the red screen still appears with the error Unable to download js bundle.
What could be the problem?
You are working fine. for this problem have added the IP address in device Setting server host. one more thing your machine and device should have on same network.