Rocket.Chat.ReactNative/android/build.gradle

// Top-level build file where you can add configuration options common to all sub-projects/modules.

buildscript {
    repositories {
        google()
        mavenLocal()
        mavenCentral()
        jcenter()
    }
    dependencies {
        // classpath 'com.android.tools.build:gradle:2.2.3'
        classpath 'com.android.tools.build:gradle:3.1.0'

        // NOTE: Do not place your application dependencies here; they belong
        // in the individual module build.gradle files
    }
}

allprojects {
    repositories {
        mavenLocal()
        mavenCentral()
        jcenter()
        google()
        maven {
            url 'https://maven.google.com'
        }
        maven { url "https://jitpack.io" }
        maven {
            // All of React Native (JS, Obj-C sources, Android binaries) is installed from npm
            url "$rootDir/../node_modules/react-native/android"
        }
        maven {
            // Local Maven repo containing AARs with JSC library built for Android
            url "$rootDir/../node_modules/jsc-android/dist"
        }
    }
}

subprojects {
    afterEvaluate {
        android {
            compileSdkVersion 27
            buildToolsVersion "27.0.3"
            defaultConfig {
                targetSdkVersion 27
            }
        }
    }
}