transformClassesAndResourcesWithProguardForRelease FAILED

I have changed nothing just comment

// shrinkResources true
// minifyEnabled true

you don't want to change any proguard file I have already searched for this issue after 2days wasted

Try adding this code to your proGuard rules, it worked for me

-ignorewarnings
-keep class * {
    public private *;
}

The answer was posted here: Execution failed for task ':app:transformClassesAndResourcesWithProguardForRelease

It worked for me I also had to add following in a pro-gaurd.txt file

#### -- Picasso --
 -dontwarn com.squareup.picasso.**

 #### -- OkHttp --

 -dontwarn com.squareup.okhttp.internal.**

 #### -- Apache Commons --

 -dontwarn org.apache.commons.logging.**

     -ignorewarnings 
-keep class * {
public private protected *;
}

add this code to ..your-project/app/proguard-rules.pro

 -ignorewarnings

your signed apk will be generated successfully...

Update :

That's better to fix your warning messages using -dontwarn or -keep keys on your proguard-rules.pro... Because if you use (maybe your libraries) java reflection in your code the application will be crashed...