Android Studio, ProGuard unable to compute hash of Classes.jar

Question

It has been long years, if ever since I've asked a question at StackOverflow. Although I use it almost of daily basis. Anyway; here it goes:

Recently I've switched to API 23; that forced me to use

 useLibrary 'org.apache.http.legacy'

as they've thrown out an easy access to the apache library.

My project compiles fine and runs fine across all test-devices in debug mode. Today I need to bring my project to production and ProGuard shouts with

Unable to compute hash of (..) \build\intermediates\classes-proguard\release\classes.jar'

there are no other errors or warning. There used to be but I got rid of them. Like getting rid of duplicate copies of apache libraries.

Here is my Gradle file:

buildscript {
    repositories {
        mavenCentral()
        jcenter()
    }

    dependencies {
        classpath 'com.android.tools.build:gradle:1.3.1'

    }
}

apply plugin: 'com.android.application'

repositories {
    maven { url "http://dl.bintray.com/populov/maven" }
    mavenCentral()
    jcenter()
}


dependencies {
    compile 'com.github.lzyzsd:circleprogress:1.1.0@aar'
    compile('com.fasterxml.jackson.datatype:jackson-datatype-joda:2.0.4') {
        exclude module: 'joda-time'
    }
    compile 'net.danlew:android.joda:2.8.1'
    compile "commons-io:commons-io:+"
    compile 'com.google.android.gms:play-services-location:7.8.0'
    compile 'com.google.android.gms:play-services-nearby:7.8.0'
    compile ('com.google.apis:google-api-services-translate:v2-rev41-1.20.0')
            {
                // Exclude artifacts that the Android SDK/Runtime provides.
                exclude group: 'xpp3', module: 'shared'
                exclude group: 'org.apache.httpcomponents', module: 'httpclient'
                exclude group: 'junit', module: 'junit'
                exclude group: 'com.google.android', module: 'android'
            }
    compile ('com.google.http-client:google-http-client-android:1.18.0-rc')
            {
                // Exclude artifacts that the Android SDK/Runtime provides.
                exclude group: 'xpp3', module: 'shared'
                exclude group: 'org.apache.httpcomponents', module: 'httpclient'
                exclude group: 'junit', module: 'junit'
                exclude group: 'com.google.android', module: 'android'
            }

    compile 'com.theartofdev.edmodo:android-image-cropper:1.0.+'
    compile 'com.viewpagerindicator:library:2.4.1@aar'
    compile 'me.leolin:ShortcutBadger:1.0.10@aar'
    compile 'com.android.support:appcompat-v7:23.0.+'
    compile "com.android.support:support-v4:23.0.+"
    compile "com.android.support:gridlayout-v7:23.0.+"
    compile "com.android.support:cardview-v7:23.0.+"
    compile (
            [group: 'com.fasterxml.jackson.core', name: 'jackson-core', version: '2.4.1'],
            [group: 'com.fasterxml.jackson.core', name: 'jackson-annotations', version: '2.4.1'],
            [group: 'com.fasterxml.jackson.core', name: 'jackson-databind', version: '2.4.1']
    )
    compile 'de.undercouch:bson4jackson:2.4.0'

}

// The sample build uses multiple directories to
// keep boilerplate and common code separate from
// the main sample code.
List<String> dirs = [
    'main',     // main sample code; look here for the interesting stuff.
    'common',   // components that are reused by multiple samples
    'template'] // boilerplate code that is generated by the sample template process

android {
    compileSdkVersion 23
    buildToolsVersion "23.0.0"
    useLibrary 'org.apache.http.legacy'
    defaultConfig {
        minSdkVersion 10
        targetSdkVersion 23
    }
    buildTypes {
        debug {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'

        }
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.txt'
        }
    }
    sourceSets {
        main {
            dirs.each { dir ->
                java.srcDirs "src/${dir}/java"
                res.srcDirs "src/${dir}/res"
            }
        }
        androidTest.setRoot('tests')
        androidTest.java.srcDirs = ['tests/src']

    }
    packagingOptions {
        exclude 'META-INF/NOTICE'
        exclude 'META-INF/NOTICE.txt'
        exclude 'META-INF/LICENSE'
        exclude 'META-INF/LICENSE.txt'
    }

}

and here goes the proguard-rules.txt

# Add project specific ProGuard rules here.
# By default, the flags in this file are appended to flags specified
# in C:\android-sdk/tools/proguard/proguard-android.txt
# You can edit the include path and order by changing the proguardFiles
# directive in build.gradle.
#
# For more details, see
#   http://developer.android.com/guide/developing/tools/proguard.html

# Only obfuscate


-dontshrink

# Keep source file and line numbers for better crash logs
-keepattributes SourceFile,LineNumberTable

# Avoid throws declarations getting removed from retrofit service definitions
-keepattributes Exceptions

# Allow obfuscation of android.support.v7.internal.view.menu.**
# to avoid problem on Samsung 4.2.2 devices with appcompat v21
# see https://code.google.com/p/android/issues/detail?id=78377
-keep class !android.support.v7.internal.view.menu.** { *; }

# Amazon IAP library has some missing stuff
-dontwarn com.amazon.**

# ButterKnife uses some annotations not available on Android.
-dontwarn butterknife.internal.**
# Prevent ButterKnife annotations from getting renamed.
-keepnames class * { @butterknife.InjectView *;}

# Eventbus methods can not be renamed.
-keepclassmembers class ** {
    public void onEvent*(**);
}

# Gson uses generic type information stored in a class file when working with fields. Proguard
# removes such information by default, so configure it to keep all of it.
-keepattributes Signature
# Gson specific classes
-dontwarn sun.misc.Unsafe

# joda-time has some annotations we don't care about.
-dontwarn org.joda.convert.**

# OkHttp has some internal stuff not available on Android.
-dontwarn com.squareup.okhttp.internal.**

# Okio has some stuff not available on Android.
-dontwarn java.nio.file.*
-dontwarn org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement

# Oltu has some stuff not available on Android (javax.servlet), we don't use (slf4j)
# and not included because it is available on Android (json).
-dontwarn javax.servlet.http.**
-dontwarn org.slf4j.**
-dontwarn org.json.**
-dontwarn com.fasterxml.**

# Retrofit has some optional dependencies we don't use.
-dontwarn rx.**
-dontwarn retrofit.appengine.**

I've cleaned my project; restarted Android Stuio even wiped out the whole Builds directory.

Result:
Information:Gradle tasks [:Application:assembleRelease]
:Application:preBuild UP-TO-DATE
:Application:preReleaseBuild UP-TO-DATE
:Application:checkReleaseManifest
:Application:preDebugBuild UP-TO-DATE
:Application:prepareComAndroidSupportAppcompatV72300Library UP-TO-DATE
:Application:prepareComAndroidSupportCardviewV72300Library UP-TO-DATE
:Application:prepareComAndroidSupportGridlayoutV72300Library UP-TO-DATE
:Application:prepareComAndroidSupportSupportV42300Library UP-TO-DATE
:Application:prepareComGithubLzyzsdCircleprogress110Library UP-TO-DATE
:Application:prepareComGoogleAndroidGmsPlayServicesBase780Library UP-TO-DATE
:Application:prepareComGoogleAndroidGmsPlayServicesLocation780Library UP-TO-DATE
:Application:prepareComGoogleAndroidGmsPlayServicesMaps780Library UP-TO-DATE
:Application:prepareComGoogleAndroidGmsPlayServicesNearby780Library UP-TO-DATE
:Application:prepareComTheartofdevEdmodoAndroidImageCropper104Library UP-TO-DATE
:Application:prepareComViewpagerindicatorLibrary241Library UP-TO-DATE
:Application:prepareMeLeolinShortcutBadger1010Library UP-TO-DATE
:Application:prepareNetDanlewAndroidJoda281Library UP-TO-DATE
:Application:prepareReleaseDependencies
:Application:compileReleaseAidl UP-TO-DATE
:Application:compileReleaseRenderscript UP-TO-DATE
:Application:generateReleaseBuildConfig UP-TO-DATE
:Application:generateReleaseAssets UP-TO-DATE
:Application:mergeReleaseAssets UP-TO-DATE
:Application:generateReleaseResValues UP-TO-DATE
:Application:generateReleaseResources UP-TO-DATE
:Application:mergeReleaseResources UP-TO-DATE
:Application:processReleaseManifest UP-TO-DATE
:Application:processReleaseResources UP-TO-DATE
:Application:generateReleaseSources UP-TO-DATE
:Application:processReleaseJavaRes UP-TO-DATE
:Application:compileReleaseJavaWithJavac UP-TO-DATE
:Application:compileReleaseNdk UP-TO-DATE
:Application:compileReleaseSources UP-TO-DATE
:Application:lintVitalRelease
:Application:proguardRelease UP-TO-DATE
:Application:dexRelease UP-TO-DATE
:Application:validateExternalOverrideSigning
:Application:packageRelease FAILED
Error:Execution failed for task ':Application:packageRelease'.
> Unable to compute hash of C:\Users\rafal_000\Projekty\Application\build\intermediates\classes-proguard\release\classes.jar
Information:BUILD FAILED
Information:Total time: 6.694 secs
Information:1 error
Information:0 warnings
Information:See complete output in console

Answer 1

As Iagreen has noted in his comment; I used the gradlew command line utility to get more detailed errors. It turned out there was a problem with JAVA_HOME variable. Solved.