After upgrade android version getting "Duplicate class android.support.v4.app.INotificationSideChannel"

Question

before android update 3.4 my application run perfectly but after upgrade android my application getting merging error:

"Duplicate class android.support.v4.app.INotificationSideChannel"

android update 3.4
upgrade gradle 5.1.1 
upgrade sdk

Error:
    Duplicate class android.support.v4.app.INotificationSideChannel found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.app.INotificationSideChannel$Stub found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.app.INotificationSideChannel$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.IResultReceiver found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.IResultReceiver$Stub found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.IResultReceiver$Stub$Proxy found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.ResultReceiver found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.ResultReceiver$1 found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.ResultReceiver$MyResultReceiver found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class android.support.v4.os.ResultReceiver$MyRunnable found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class androidx.core.graphics.drawable.IconCompatParcelizer found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class androidx.core.internal.package-info found in modules classes.jar (androidx.core:core:1.0.0) and classes.jar (com.android.support:support-compat:28.0.0)
    Duplicate class androidx.versionedparcelable.CustomVersionedParcelable found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.NonParcelField found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.ParcelField found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.ParcelImpl found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.ParcelImpl$1 found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.ParcelUtils found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcel found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcel$1 found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcel$ParcelException found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcelParcel found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcelStream found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcelStream$FieldBuffer found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcelStream$InputBuffer found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcelable found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)
    Duplicate class androidx.versionedparcelable.VersionedParcelize found in modules classes.jar (androidx.versionedparcelable:versionedparcelable:1.0.0) and classes.jar (com.android.support:versionedparcelable:28.0.0)

Go to the documentation to learn how to Fix dependency resolution errors.

------------------DEPENDENCY------------

dependencies {
    implementation fileTree(include: ['*.jar'], dir: 'libs')
    //noinspection GradleCompatible
    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:design:28.0.0'
    //noinspection GradleCompatible
//    implementation 'com.android.support:appcompat-v7:28.0.0'
    implementation 'com.android.support:support-compat:28.0.0'
    implementation 'com.android.support.constraint:constraint-layout:2.0.0-alpha4'
//    implementation 'com.android.support:design:28.0.0'
    testImplementation 'junit:junit:4.13-beta-2'
    androidTestImplementation 'com.android.support.test:runner:1.0.2'
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.2'
    //volley
    implementation 'com.android.volley:volley:1.1.0'
    //crop image library...
    implementation 'com.theartofdev.edmodo:android-image-cropper:2.8.0'
    //ButterKnife
    implementation 'com.jakewharton:butterknife:8.8.1'
    annotationProcessor 'com.jakewharton:butterknife-compiler:8.8.1'
    //retrofit
    implementation 'com.squareup.retrofit2:retrofit:2.5.0'
    implementation 'com.squareup.retrofit2:converter-gson:2.5.0'
    implementation 'com.squareup.retrofit2:adapter-rxjava:2.5.0'
    implementation 'io.reactivex:rxandroid:1.2.1'
    implementation 'com.github.traex.rippleeffect:library:1.3'
    //Google play services
    implementation 'com.google.android.gms:play-services-location:16.0.0'
    implementation 'com.google.android.gms:play-services-maps:16.1.0'
    //gson
    implementation 'com.google.code.gson:gson:2.8.5'
    // Room
    implementation 'android.arch.persistence.room:runtime:1.1.1'
    implementation 'com.android.support:support-v4:28.0.0'
    annotationProcessor "android.arch.persistence.room:compiler:1.1.1"
    implementation 'org.jsoup:jsoup:1.11.3'
    //cardview & recyclerview
    implementation 'com.android.support:cardview-v7:28.0.0'
    implementation 'com.android.support:recyclerview-v7:28.0.0'
    //picasoo
    implementation 'com.squareup.picasso:picasso:2.71828'
    implementation 'com.android.support:support-annotations:28.0.0'
    implementation 'de.hdodenhof:circleimageview:3.0.0'
    implementation 'com.karumi:dexter:5.0.0'
    implementation 'com.journeyapps:zxing-android-embedded:3.4.0'
    //firebase
    implementation 'com.google.firebase:firebase-core:16.0.8'
    implementation 'com.google.firebase:firebase-ml-vision:19.0.3'
    //firebase-cloud massaging..
    implementation 'com.google.firebase:firebase-messaging:17.6.0'
    implementation "org.jetbrains.kotlin:kotlin-stdlib-jdk7:$kotlin_version"
}

Answer 1

Why did this happen?

Because after upgrade, androidx.core:core is accessed somewhere, when your project is still not using androidx. So classes like INotificationSideChannel and many others are now found at two places - androidx.core:core and com.android.support:support-compat. That's why this error occured.

Solution?

You need to migrate to AndroidX which you should have done already. If you don't know about AndroidX. Please read What is AndroidX?

How to migrate current project

In Android Studio 3.2 (September 2018), there is direct option to migrate existing project to AndroidX. This refract all packages automatically.

Before you migrate, it is strongly recommended to backup your project.

Existing project

• Android Studio > Refactor Menu > Migrate to AndroidX...
• It will analysis and will open Refractor window in bottom. Accept changes to be done.

New project

Put these flags in your gradle.properties

android.enableJetifier=true
android.useAndroidX=true

Check @Library mappings for equal AndroidX package.

Check @Official page of Migrate to AndroidX

Answer 2

You have androidx libraries (probably in one of the used libraries) conflicting with the support libraries.

Add these lines into your gradle.properties file: (It's in the root directory of your project)

android.useAndroidX=true
android.enableJetifier=true

The Jetifier tool migrates support-library-dependent libraries to rely on the equivalent AndroidX packages instead.