title: android DexArchiveMergerException: Unable to merge dex
body: <p>I have recently updated my <code>android sdk version from 25 to 26.</code> After updating the <code>app</code>, i'm receiving this error:</p>
  
  <pre><code>Error:Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
  &gt; com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex
  </code></pre>
  
  <p>This is my gradle file:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 26
      defaultConfig {
          applicationId "com.hago.ntr"
          minSdkVersion 15
          targetSdkVersion 26
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner
         "android.support.test.runner.AndroidJUnitRunner"
      }
  
      buildTypes {
           release {
               minifyEnabled false
               proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      implementation 'com.android.support:appcompat-v7:26.1.0'
      implementation 'com.android.support:design:26.1.0'
      implementation 'com.android.support.constraint:constraint-layout:1.0.2'
      testImplementation 'junit:junit:4.12'
      androidTestImplementation 'com.android.support.test:runner:1.0.1'
      androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
      implementation 'com.facebook.android:facebook-android-sdk:4.5.0'
      implementation 'com.twitter.sdk.android:tweet-ui:3.1.1'
      implementation files('libs/picasso-2.5.2.jar')
      implementation files('libs/YouTubeAndroidPlayerApi.jar')
  }
  </code></pre>
  
  <p>Please suggest any changes. I have tried <code>clean and re-build</code> but the error still exists. I have been trying for solution to this from last week</p>
  
  <p>Please find the error i got here:</p>
  
  <pre><code>Exception is:
   org.gradle.api.tasks.TaskExecutionException: Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:100)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.execute(ExecuteActionsTaskExecuter.java:70)
  at org.gradle.api.internal.tasks.execution.SkipUpToDateTaskExecuter.execute(SkipUpToDateTaskExecuter.java:63)
  at org.gradle.api.internal.tasks.execution.ResolveTaskOutputCachingStateExecuter.execute(ResolveTaskOutputCachingStateExecuter.java:54)
  at org.gradle.api.internal.tasks.execution.ValidatingTaskExecuter.execute(ValidatingTaskExecuter.java:58)
  at org.gradle.api.internal.tasks.execution.SkipEmptySourceFilesTaskExecuter.execute(SkipEmptySourceFilesTaskExecuter.java:88)
  at org.gradle.api.internal.tasks.execution.ResolveTaskArtifactStateTaskExecuter.execute(ResolveTaskArtifactStateTaskExecuter.java:52)
  at org.gradle.api.internal.tasks.execution.SkipTaskWithNoActionsExecuter.execute(SkipTaskWithNoActionsExecuter.java:52)
  at org.gradle.api.internal.tasks.execution.SkipOnlyIfTaskExecuter.execute(SkipOnlyIfTaskExecuter.java:54)
  at org.gradle.api.internal.tasks.execution.ExecuteAtMostOnceTaskExecuter.execute(ExecuteAtMostOnceTaskExecuter.java:43)
  at org.gradle.api.internal.tasks.execution.CatchExceptionTaskExecuter.execute(CatchExceptionTaskExecuter.java:34)
  at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker$1.run(DefaultTaskGraphExecuter.java:248)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:197)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:107)
  at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:241)
  at org.gradle.execution.taskgraph.DefaultTaskGraphExecuter$EventFiringTaskWorker.execute(DefaultTaskGraphExecuter.java:230)
  at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.processTask(DefaultTaskPlanExecutor.java:124)
  at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.access$200(DefaultTaskPlanExecutor.java:80)
  at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker$1.execute(DefaultTaskPlanExecutor.java:105)
  at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker$1.execute(DefaultTaskPlanExecutor.java:99)
  at org.gradle.execution.taskgraph.DefaultTaskExecutionPlan.execute(DefaultTaskExecutionPlan.java:625)
  at org.gradle.execution.taskgraph.DefaultTaskExecutionPlan.executeWithTask(DefaultTaskExecutionPlan.java:580)
  at org.gradle.execution.taskgraph.DefaultTaskPlanExecutor$TaskExecutorWorker.run(DefaultTaskPlanExecutor.java:99)
  at org.gradle.internal.concurrent.ExecutorPolicy$CatchAndRecordFailures.onExecute(ExecutorPolicy.java:63)
  at org.gradle.internal.concurrent.ManagedExecutorImpl$1.run(ManagedExecutorImpl.java:46)
  at org.gradle.internal.concurrent.ThreadFactoryImpl$ManagedThreadRunnable.run(ThreadFactoryImpl.java:55)
  
  Caused by: java.lang.RuntimeException: java.lang.RuntimeException:    java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex
  at com.android.builder.dexing.DxDexArchiveMerger.mergeMonoDex(DxDexArchiveMerger.java:177)
  at com.android.builder.dexing.DxDexArchiveMerger.mergeDexArchives(DxDexArchiveMerger.java:118)
  at com.android.build.gradle.internal.transforms.DexMergerTransformCallable.call(DexMergerTransformCallable.java:97)
  at com.android.build.gradle.internal.transforms.ExternalLibsMergerTransform.transform(ExternalLibsMergerTransform.kt:121)
  at com.android.build.gradle.internal.pipeline.TransformTask$2.call(TransformTask.java:222)
  at com.android.build.gradle.internal.pipeline.TransformTask$2.call(TransformTask.java:218)
  at com.android.builder.profile.ThreadRecorder.record(ThreadRecorder.java:102)
  at com.android.build.gradle.internal.pipeline.TransformTask.transform(TransformTask.java:213)
  at org.gradle.internal.reflect.JavaMethod.invoke(JavaMethod.java:73)
  at org.gradle.api.internal.project.taskfactory.DefaultTaskClassInfoStore$IncrementalTaskAction.doExecute(DefaultTaskClassInfoStore.java:173)
  at org.gradle.api.internal.project.taskfactory.DefaultTaskClassInfoStore$StandardTaskAction.execute(DefaultTaskClassInfoStore.java:134)
  at org.gradle.api.internal.project.taskfactory.DefaultTaskClassInfoStore$StandardTaskAction.execute(DefaultTaskClassInfoStore.java:121)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter$1.run(ExecuteActionsTaskExecuter.java:122)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:336)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor$RunnableBuildOperationWorker.execute(DefaultBuildOperationExecutor.java:328)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.execute(DefaultBuildOperationExecutor.java:197)
  at org.gradle.internal.progress.DefaultBuildOperationExecutor.run(DefaultBuildOperationExecutor.java:107)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeAction(ExecuteActionsTaskExecuter.java:111)
  at org.gradle.api.internal.tasks.execution.ExecuteActionsTaskExecuter.executeActions(ExecuteActionsTaskExecuter.java:92)
  ... 27 more
  Caused by: java.lang.RuntimeException: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex
  at com.android.builder.dexing.DxDexArchiveMerger.lambda$mergeMonoDex$0(DxDexArchiveMerger.java:171)
  
  Caused by: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex
  Caused by: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex
  at com.android.builder.dexing.DexArchiveMergerCallable.call(DexArchiveMergerCallable.java:72)
  at com.android.builder.dexing.DexArchiveMergerCallable.call(DexArchiveMergerCallable.java:36)
  
  Caused by: com.android.dex.DexException: Multiple dex files define  Lcom/squareup/picasso/Cache;
  at com.android.dx.merge.DexMerger.readSortableTypes(DexMerger.java:661)
  at com.android.dx.merge.DexMerger.getSortedTypes(DexMerger.java:616)
  at com.android.dx.merge.DexMerger.mergeClassDefs(DexMerger.java:598)
  at com.android.dx.merge.DexMerger.mergeDexes(DexMerger.java:171)
  at com.android.dx.merge.DexMerger.merge(DexMerger.java:198)
  at com.android.builder.dexing.DexArchiveMergerCallable.call(DexArchiveMergerCallable.java:61)
  ... 1 more
  </code></pre>
  
  <p>Thank You in advance</p>