React Native Execution failed for task ':app:checkDebugDuplicateClasses'

Question

• What went wrong: Execution failed for task ':app:checkDebugDuplicateClasses'.

A failure occurred while executing com.android.build.gradle.internal.tasks.CheckDuplicatesRunnable Duplicate class android.support.v4.app.INotificationSideChannel found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.IResultReceiver found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.IResultReceiver$Stub found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.IResultReceiver$Stub$Proxy found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.ResultReceiver found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.ResultReceiver$1 found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.ResultReceiver$MyResultReceiver found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1) Duplicate class android.support.v4.os.ResultReceiver$MyRunnable found in modules core-1.9.0.aar -> core-1.9.0-runtime (androidx.core:core:1.9.0) and support-compat-27.1.1.aar -> support-compat-27.1.1-runtime (com.android.support:support-compat:27.1.1)

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BUILD FAILED in 10s

I got this problem while running my React native CLI project

Answer 1

This Error is due to missing line in your android/gradle.properties

Steps Go to your android/gradle.properties and check for this line

 **1.(android.useAndroidX=true)**
 **2.(android.enableJetifier=true)**

if one of these lines are missing just add those to your android/gradle.properties

And it should resolve the problem.