title: Android Studio 3.0 Execution failed for task: unable to merge dex
body: <p>android studio was getting build error while build execution with following: </p>
  
  <blockquote>
    <p>Error:Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'. java.lang.RuntimeException: java.lang.RuntimeException: com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex"</p>
  </blockquote>
  
  <p>My app:build.gradle file:</p>
  
  <pre><code>apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 26
      buildToolsVersion '26.0.2'
      defaultConfig {
          applicationId "com.pdroid.foodieschoice"
          minSdkVersion 16
          targetSdkVersion 25
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
          exclude group: 'com.android.support', module: 'support-annotations'
      })
      compile 'com.android.support.constraint:constraint-layout:1.0.2'
      compile 'com.firebaseui:firebase-ui-auth:2.3.0'
  
      testCompile 'junit:junit:4.12'
  }
  configurations.all {
      resolutionStrategy {
          force 'com.android.support:appcompat-v7:26.0.1'
          force 'com.android.support:support-compat:26.0.1'
          force 'com.android.support:support-core-ui:26.0.1'
          force 'com.android.support:support-annotations:26.0.1'
          force 'com.android.support:recyclerview-v7:26.0.1'
      }
  }
  
  apply plugin: 'com.google.gms.google-services'
  </code></pre>
  
  <p>any solutions</p>
  
  <p>Edit: i have done with sample through firebase github site and solved</p>