How do I fix this "Duplicate class error" in Android Studio

Question

I updated implementation com.google.android.gms:play-services-ads:19.8.0 to implementation com.google.android.gms:play-services-ads:20.4.0 and now I get this error:

Duplicate class com.google.android.gms.internal.measurement.zzbs found in modules jetified-play-services-measurement-18.0.2-runtime (com.google.android.gms:play-services-measurement:18.0.2) and jetified-play-services-measurement-sdk-api-18.0.3-runtime (com.google.android.gms:play-services-measurement-sdk-api:18.0.3)
Duplicate class com.google.android.gms.internal.measurement.zzl found in modules jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2) and jetified-play-services-measurement-sdk-api-18.0.3-runtime (com.google.android.gms:play-services-measurement-sdk-api:18.0.3)
Duplicate class com.google.android.gms.measurement.internal.zzfh found in modules jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3) and jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2)
Duplicate class com.google.android.gms.measurement.internal.zzgn found in modules jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3) and jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2)
Duplicate class com.google.android.gms.measurement.internal.zzgo found in modules jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3) and jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2)
Duplicate class com.google.android.gms.measurement.internal.zzgp found in modules jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3) and jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2)
Duplicate class com.google.android.gms.measurement.internal.zzgq found in modules jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3) and jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2)
Duplicate class com.google.android.gms.measurement.internal.zzhs found in modules jetified-play-services-measurement-18.0.2-runtime (com.google.android.gms:play-services-measurement:18.0.2) and jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3)
Duplicate class com.google.android.gms.measurement.internal.zzhx found in modules jetified-play-services-measurement-base-18.0.3-runtime (com.google.android.gms:play-services-measurement-base:18.0.3) and jetified-play-services-measurement-impl-18.0.2-runtime (com.google.android.gms:play-services-measurement-impl:18.0.2)

How to fix this error?

Answer 1

I am having the same issue and I fixed it by downgrading play-services-ads dependency like this. So you can try.

def ads_version = "20.3.0"
implementation "com.google.android.gms:play-services-ads:$ads_version"

Answer 2

I ran into the same issue today, and after many trial and errors, I finally found that it was caused by a firebase dependency. If you're using firebase in your project, make sure to use the latest BoM version in app/build.gradle:

dependencies{
   // implementation platform('com.google.firebase:firebase-bom:25.12.0')  <-- Produces errors
  implementation platform('com.google.firebase:firebase-bom:29.0.0')  //<-- This works
}

If you are not using firebase and still get this error, you can try excluding the offending classes directly in app/build.gradle:

android {
   defaultConfig {
    ...
   }
   buildTypes {
    ...
   }

   configurations {
     all {
       exclude group: "com.google.android.gms", module: "play-services-measurement-impl"
       exclude group: "com.google.android.gms", module: "play-services-measurement"
     }
   }
}

Answer 3

The error is being produced due to the conflicts between firebase & google service dependency. So you have 2 options.

You can change the versions and keep doing that until you find the perfect working combination which is time consuming or you can find a solution that works every time so you don't have to play with the versions every time. You just use that solution wherever you get such error.

Here, you need to use the updated method of injecting the firebase dependency as shown in the official documentation.

Put this line in your dependency :

implementation platform('com.google.firebase:firebase-bom:28.1.0')

Then, You can use any firebase dependency without specifying the versions, and it will work flawlessly all the time!

The final code looks like this,

implementation platform('com.google.firebase:firebase-bom:28.1.0')
implementation 'com.google.firebase:firebase-analytics'
implementation 'com.google.firebase:firebase-config'
implementation 'com.google.firebase:firebase-crashlytics'

And it won't produce any duplication related errors with the play-services dependency.