1My app kept crashing because I had changed the name of the app in a few places. 
2Make sure your app name is the same everywhere. Check if the folder name in
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4  android/app/src/main/java/com/<appname>/MainActivity.java
5  android/app/src/main/java/com/<appname>/MainApplication.java
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7has the same name as that of your app in manifest file in
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9	android/app/src/main/AndroidManifest.xml
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11  
12##### Another solution ########
131. clean your build 
14cd android ./gradlew clean
15
162. Try bundling 
17./gradlew bundleRelease
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193. Exit android folder 
20cd ../
21
224. Try running 
23npx react-native run-android --variant=release