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gradle – can't generate signed APK from Android studio "Execution failed for task ':packageRelease'"

Posted by: admin April 23, 2020 Leave a comment


I am using Android Studio 1.2.2 and tried to generate APK with proguard setting. But I can’t do it and got below error message.

“Execution failed for task ‘:packageRelease’.

Unable to compute hash of /Users/Documents/projectX/app/build/intermediates/classes-proguard/release/classes.jar “

The proguard setting is just simple.


And the gradle file is below.

apply plugin: 'com.android.application'
apply plugin: 'com.google.gms.google-services'

android {
    compileSdkVersion "Google Inc.:Google APIs:22"
    buildToolsVersion "21.1.2"

    defaultConfig {
        applicationId "com.bientus.cirque.sansotong"
        minSdkVersion 15
        targetSdkVersion 22
        versionCode 1
        versionName "1.0"
//        multiDexEnabled true
    buildTypes {
        debug {
            debuggable true

        release {
            minifyEnabled true
            //proguardFiles 'proguard-project.txt', 'proguard.cfg'
            //proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-project.txt', 'proguard.cfg'
            proguardFiles 'proguard-project.txt'

dependencies {
        compile fileTree(dir: 'libs', include: ['*.jar'])
        compile 'com.android.support:appcompat-v7:22.0.0'
        compile "com.google.android.gms:play-services:7.5.0"
//    compile 'com.android.support:multidex:1.0.0'

buildscript {
    repositories {
//        mavenCentral()
    dependencies {
        classpath 'com.android.tools.build:gradle:1.2.3'
        classpath 'com.google.gms:google-services:1.3.0-beta1'

Can anybody give any idea or thought?
Thank you very much!

How to&Answers:

Just add to the project’s proguard-rules:

-keep public class com.google.android.gms.**
-dontwarn com.google.android.gms.**


It worked after setting followings in ‘proguard-project.txt’.
Obviously the gradle should be set for this file.

-dontwarn android.support.v7.**
-keep class android.support.v7.** { *; }
-keep interface android.support.v7.** { *; }


Look at your build output. You might have proguard warnings in there, like if you have 2 libraries that share some class (with potentialy different versions).

This might prevent proguard to compute an hash.

I had the same issue while having both openIAB and opfIAB (both use Amazon and google IAB) in my build. Removing one of these libs resolved my issue


OK! its very easy ! just following step by step:
build.gradle :minifyEnabled false -> minifyEnabled true
proguard-rules.pro :
you have to add third libraries that you use in your project like piccaso and etc.
if you do this in android studio , it decline this files.

-dontwarn android.support.**
-dontwarn com.github.**
-dontwarn com.squareup.picasso.**
-dontwarn com.etsy.android.grid.**

it works 🙂


I had the problem too and the best way to solve it is:
Go to the gradle console and see where there is a warning e.g

Warning: com.squareup.picasso.OkHttpDownloader: can’t find referenced class com.squareup.okhttp.OkHttpClient

Now open the proguard rules file and scroll to the bottom and add the line

-dontwarn com.squareup.okhttp.**

For any missing classes that you find on the gradle console you basically add the line

-dontwarn followed by class name 

Hope this works for everyone too. Good luck!