Generate Signed APK: Errors while building APK Android Studio

Question

I am unable to generate Signed APK using minifyEnabled true and shrinkResources true

App Level : build.gradle

buildscript {
    repositories {
        mavenCentral()
    }
    dependencies {
        classpath 'com.android.tools.build:gradle:2.1.0'
    }
}
apply plugin: 'com.android.application'

repositories {
    mavenCentral()
}

android {
    compileSdkVersion 23
    buildToolsVersion '22.0.1'

    defaultConfig {
        applicationId "......."
        minSdkVersion 14
        targetSdkVersion 21
        versionCode 1
        versionName "1.0"
        testInstrumentationRunner "android.support.test.runner.AndroidJUnitRunner"
    }
    buildTypes {
        debug {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }

        release {
            minifyEnabled true
            shrinkResources true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    configurations {
        compile.exclude group: "org.apache.httpcomponents", module: "httpclient"
    }
}

dependencies {
    compile 'com.android.support:design:23.0.1'
    compile 'com.android.support:cardview-v7:23.0.1'
    compile 'com.android.support:recyclerview-v7:23.0.1'
    compile 'com.android.support:appcompat-v7:23.0.1'
    compile 'com.squareup.picasso:picasso:2.5.2'
    compile 'com.google.apis:google-api-services-youtube:v3-rev149-1.20.0'
    compile 'com.google.http-client:google-http-client-android:1.20.0'
    compile 'com.google.api-client:google-api-client-android:1.20.0'
    compile 'com.google.api-client:google-api-client-gson:1.20.0'
    compile files('libs/YouTubeAndroidPlayerApi.jar')
    compile 'com.github.clans:fab:1.6.2'
}

MessageView

Information:Gradle tasks [:app:assembleRelease]
:app:preBuild UP-TO-DATE
:app:preReleaseBuild UP-TO-DATE
:app:checkReleaseManifest
:app:preDebugBuild UP-TO-DATE
:app:prepareComAndroidSupportAppcompatV72301Library UP-TO-DATE
:app:prepareComAndroidSupportCardviewV72301Library UP-TO-DATE
:app:prepareComAndroidSupportDesign2301Library UP-TO-DATE
:app:prepareComAndroidSupportRecyclerviewV72301Library UP-TO-DATE
:app:prepareComAndroidSupportSupportV42301Library UP-TO-DATE
:app:prepareComGithubClansFab162Library UP-TO-DATE
:app:prepareReleaseDependencies
:app:compileReleaseAidl
:app:compileReleaseRenderscript
:app:generateReleaseBuildConfig
:app:generateReleaseAssets UP-TO-DATE
:app:mergeReleaseAssets
:app:generateReleaseResValues UP-TO-DATE
:app:generateReleaseResources
:app:mergeReleaseResources
:app:processReleaseManifest
:app:processReleaseResources
:app:generateReleaseSources
:app:processReleaseJavaRes UP-TO-DATE
:app:compileReleaseJavaWithJavac
Note: .....YouTubeRecyclerViewFragment.java uses or overrides a deprecated API.
Note: Recompile with -Xlint:deprecation for details.
Note: ....GetPlaylistAsyncTask.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
:app:compileReleaseNdk UP-TO-DATE
:app:compileReleaseSources
:app:proguardRelease UP-TO-DATE
:app:dexRelease
:app:shrinkReleaseResources
Removed unused resources: Binary resource data reduced from 741KB to 402KB: Removed 45%
Note: If necessary, you can disable resource shrinking by adding
android {
    buildTypes {
        release {
            shrinkResources false
        }
    }
}
:app:validateExternalOverrideSigning
:app:packageRelease FAILED
Error:Execution failed for task ':app:packageRelease'.
> Unable to compute hash of ....\app\build\intermediates\classes-proguard\release\classes.jar
Information:BUILD FAILED
Information:Total time: 7.45 secs
Information:1 error
Information:0 warnings
Information:See complete output in console

Answer 1

You are getting

Removed unused resources: Binary resource data reduced from 741KB to 402KB: Removed 45%
Note: If necessary, you can disable resource shrinking by adding
android {
    buildTypes {
        release {
            shrinkResources false
        }
    }
}
:app:validateExternalOverrideSigning
:app:packageRelease FAILED
Error:Execution failed for task ':app:packageRelease'.

Resource shrinking works only in conjunction with code shrinking.

minifyEnabled is an Android tool that will decrease the size of your application when you go to build it .

android {

    buildTypes {
        release {
            shrinkResources true // This must be first 
            minifyEnabled true   // This must be after shrinkResources 
            proguardFiles getDefaultProguardFile('proguard-android.txt'),
                    'proguard-rules.pro'
        }
    }
}

If you haven't already built your app using minifyEnabled for code shrinking, then try that before enabling shrinkResources, because you might need to edit your proguard-rules.pro file to keep classes or methods that are created or invoked dynamically before you start removing resources.

Please read official Guideline about Shrink Your Code and Resources

Advice

Use latest version

compileSdkVersion 25
buildToolsVersion '25.0.1'
targetSdkVersion 25
compile 'com.android.support:appcompat-v7:25.1.0' // set other 25.1.0

NOTE

YouTubeRecyclerViewFragment.java uses or overrides a deprecated API.

Use Alternate Latest Version .

Answer 2

First check whether you really need to use shrinkResources

If so, do as suggested in developers link https://developer.android.com/studio/build/shrink-code.html#shrink-resources mentioned above by IntelliJ Amiya, you have to use like below

android {

    buildTypes {
        release {
            shrinkResources true  // -- always add this above minifyEnabled --
            minifyEnabled true   
            proguardFiles getDefaultProguardFile('proguard-android.txt'),
                    'proguard-rules.pro'
        }
    }
}