delete the .gradle file in android folder(u can do it manually,close every terminal and then delete it manually).now go to android folder again(cd android) and type this .\gradlew clean or gradlew.bat clean) if this gradlew.bat clean does not work then--- go to android studio ,copy the sdk path.now go to android folder again make a local.properties file add sdk.dir=your sdk path(that u got from android studio but with double slash i.e.\eg.c\users\user like this).now open enviornment variable(type env in search ) go to enviornment variables ,under system variables add variable name:ANDROID_HOME ,value:paste your sdk path(u can get it from android studio) and restart your terminal. now open your terminal, go to project directory->android and try again with this command .\gradlew bat clean. now go back to ur project directory->cd .. and type this npx react-native run-android. it took me some 15mins to build. now check ur emulator .u will find your projectapp in emulator.u can open it manually .just click once on it.it will show welcome message