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