Q:

Android Studio - Error Building - Android tasks have already been created

Getting the following error when building the project:
Error:(2, 0) Android tasks have already been created.
This happens when calling android.applicationVariants,
android.libraryVariants or android.testVariants.
Once these methods are called, it is not possible to
continue configuring the model.
Root build.gradle:
buildscript {
      repositories {
        jcenter()
      }
      dependencies {
        classpath 'com.android.tools.build:gradle:1.1.0'
      }
}
apply plugin: 'android'

android {
    compileSdkVersion 'Google Inc.:Google APIs:19'
    buildToolsVersion '19.1.0'
    defaultConfig {
       versionCode 5
       versionName '5'
       targetSdkVersion 19
       minSdkVersion 10
       applicationId 'tsp.movil'
    }
}
dependencies {
     compile 'com.google.android.gms:play-services:7.0.0'
     compile 'com.android.support:support-v4:22.1.1'
}

App build.gradle:
android {
     compileSdkVersion 'Google Inc.:Google APIs:19'
     buildToolsVersion '19.1.0'
     defaultConfig {
        applicationId "tsp.movil"
        minSdkVersion 10
        targetSdkVersion 19
        versionCode 5
        versionName '5'
     }
     buildTypes {
         release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'),      'proguard-rules.txt'
         }
     }
     productFlavors {
     }
}
dependencies {
    compile 'com.android.support:support-v4:19.1.0'
    compile 'com.google.android.gms:play-services:+'
    compile files('libs/zbar.jar')
}

A:

Your Top Level build.gradle file should only have the configuration common for all modules of your project.
make the following changes :
Root build.gradle file should have only this piece of code
buildscript {
      repositories {
        jcenter()
      }
      dependencies {
        classpath 'com.android.tools.build:gradle:1.1.0'
      }
}

allprojects{
    repositories {
        jcenter()
      }
}

