'React native run android' stop immediatelly after start the app in emulator

In my case just cleaning the cache was helpful:

npm cache clean --force  
.android/gradlew clean

I had the same issue and problem is described here port already in use. So just kill the process occupying the port.

sudo lsof -i :8081

kill -9 <PID>

i was having the same problem in ubuntu what worked for me is that i closed terminal removed my device from usb restarted. first of all would suggest you add these lines inside your packages.json replace scripts with this

"scripts": {
"prepare-repository": "npm i -g react-native-cli yarn;yarn install; react- native link",
"emulator": "emulator -avd Nexus5V6L23_x86_64 -scale 1.0",
"install": "react-native run-android",
"start": "react-native start --reset-cache",
"android": "npm run install && npm run start",
"clean": "watchman watch-del-all && npm cache clean && cd android && ./gradlew clean && cd ..",
"test": "jest"
}

After that save it and then go to the folder where u created project. lets say mine home/workspace/demo. Inside that run script

 npm run clean //this will clear all cache

after that

npm run android 

It will run app in device as well as start-reset cache.Let me know if it helps.

Sometimes adding

adb reverse tcp:8081

before running npm run android does the trick I will recommend you to enable Gradle daemon it really makes your build faster. To enable it goto android->gradle.properties and inside that file write

org.gradle.daemon=true