title: Unable to merge dex
body: <p>I have Android Studio Beta. I created a new project with compile my old modules but when I tried launching the app it did not launch with the message:</p>
  
  <pre><code>Error:Execution failed for task ':app:transformDexArchiveWithExternalLibsDexMergerForDebug'.
  </code></pre>
  
  <blockquote>
    <p>com.android.builder.dexing.DexArchiveMergerException: Unable to merge dex</p>
  </blockquote>
  
  <p>But I don't know how to solve this error. I googled this for hours but with no success. </p>
  
  <p>My project gradle:</p>
  
  <pre><code>    // Top-level build file where you can add configuration options common to all sub-projects/modules.
  
  buildscript {
      repositories {
          jcenter()
          google()
      }
      dependencies {
          classpath 'com.android.tools.build:gradle:3.0.0-beta6'
          classpath "io.realm:realm-gradle-plugin:3.7.1"
          classpath 'com.google.gms:google-services:3.1.0'
          // NOTE: Do not place your application dependencies here; they belong
          // in the individual module build.gradle files
      }
  }
  
  allprojects {
      repositories {
          jcenter()
          google()
      }
  }
  
  task clean(type: Delete) {
      delete rootProject.buildDir
  }
  </code></pre>
  
  <p>My app gradle:</p>
  
  <pre><code>    apply plugin: 'com.android.application'
  
  android {
      compileSdkVersion 26
      buildToolsVersion "26.0.1"
      defaultConfig {
          applicationId "parad0x.sk.onlyforyou"
          minSdkVersion 21
          targetSdkVersion 26
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
          multiDexEnabled true
      }
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
          debug {
          }
      }
      compileOptions {
          targetCompatibility 1.7
          sourceCompatibility 1.7
      }
      packagingOptions {
          exclude 'META-INF/LICENSE'
          exclude 'META-INF/NOTICE'
      }
      lintOptions {
          checkReleaseBuilds false
      }
      productFlavors {
      }
  }
  
  dependencies {
      compile fileTree(include: ['*.jar'], dir: 'libs')
      androidTestCompile('com.android.support.test.espresso:espresso-core:2.2.2', {
          exclude group: 'com.android.support', module: 'support-annotations'
      })
      //noinspection GradleCompatible
      compile 'com.android.support:appcompat-v7:26.0.0-alpha1'
      compile project(path: ':loginregisterview')
  
  
  }
  </code></pre>
  
  <p>And my module gradle: </p>
  
  <pre><code>    apply plugin: 'com.android.library'
  apply plugin: 'realm-android'
  
  android {
      compileSdkVersion 26
      buildToolsVersion "26.0.1"
  
      defaultConfig {
          minSdkVersion 19
          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 {
      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:appcompat-v7:26.0.2'
      compile 'com.android.support:support-v4:26.1.0'
      compile 'com.github.bumptech.glide:glide:4.0.0'
      testCompile 'junit:junit:4.12'
      compile project(path: ':parser')
  
  }
  </code></pre>
  
  <p>My second module:</p>
  
  <pre><code>     apply plugin: 'com.android.library'
  apply plugin: 'realm-android'
  
  android {
      compileSdkVersion 26
      buildToolsVersion "26.0.1"
      defaultConfig {
          minSdkVersion 14
          targetSdkVersion 23
          versionCode 1
          versionName "1.0"
          testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
  
      }
  
      realm {
          syncEnabled = true
      }
      useLibrary 'org.apache.http.legacy'
  
      buildTypes {
          release {
              minifyEnabled false
              proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
          }
      }
      productFlavors {
      }
  }
  
  dependencies {
      compile fileTree(dir: 'libs', include: ['*.jar'])
      androidTestCompile 'junit:junit:4.12'
      //  compile 'com.android.support:appcompat-v7:23.1.0'
  
      //   compile 'com.fasterxml.jackson.core:jackson-core:2.9.0'
   //   compile 'com.fasterxml.jackson.core:jackson-annotations:2.9.0'
   //   compile 'com.fasterxml.jackson.core:jackson-databind:2.9.0'
      compile 'com.google.code.gson:gson:2.6.2'
  }
  </code></pre>
  
  <p>____________finding_________</p>
  
  <p>When I did not import the second module (parser) the app did not crash on dex but when the module was not imported app did not work. :D :D </p>