proguardRelease FAILED when compiling apk with assembleRelease in Android Studio

Question

I'm trying to compile my app as assembleRelease in Android Studio 1.0.1 and get the following message:

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:proguardRelease'.
> java.io.IOException: Please correct the above warnings first.

The app compiles and runs perfectly in debug mode, and assembleRelease worked with Android Studio 0.8.

The proguard-rules.pro file is empty. The build.gradle file and the full error are shown below.

Anybody can help?

build.gradle

apply plugin: 'com.android.application'

android {
    compileSdkVersion 19
    buildToolsVersion '19.1'

    defaultConfig {
        applicationId "com.xxx.xxx"
        minSdkVersion 15
        targetSdkVersion 19
        versionCode 1
        versionName "1.0"
    }
    buildTypes {
        release {
            minifyEnabled true
            proguardFiles getDefaultProguardFile('proguard-android.txt'), 'proguard-rules.pro'
        }
    }

    lintOptions {
        abortOnError false
        absolutePaths false
        lintConfig file("lint.xml")
    }
}

repositories {
    mavenCentral()
    flatDir {
        dirs 'aars'
    }
}

dependencies {
    compile fileTree(dir: 'libs', include: ['*.jar'])
    compile 'com.urbanairship:urbanairship-lib:+@aar'
    compile 'com.google.android.gms:play-services:6.1.+'
    compile 'me.grantland:autofittextview:0.1.1@aar'
    compile 'com.google.code.gson:gson:2.2.+'
    compile 'net.danlew:android.joda:2.3.4@aar'
    compile 'com.android.support:support-v4:21.0.0'
    compile 'com.android.support:support-v13:21.0.0'
    compile 'com.squareup.okio:okio:1.0.0@jar'
    compile 'net.danlew:android.joda:2.4.0'
    compile 'de.greenrobot:eventbus:2.2.1'
    compile 'se.emilsjolander:stickylistheaders:2.5.0'
    compile 'se.emilsjolander:StickyScrollViewItems:1.1.0'
    compile 'com.nostra13.universalimageloader:universal-image-loader:1.9.3'
    compile 'com.sothree.slidinguppanel:library:2.0.2'
    compile 'com.squareup.okhttp:okhttp:2.1.0'
    compile 'com.squareup.picasso:picasso:2.4.0'
    compile 'com.squareup.okhttp:okhttp-urlconnection:2.1.0'
    compile 'de.greenrobot:eventbus:2.4.0'
}

The error is

13:40:19: Executing external task 'assembleRelease'...
:app:preBuild
:app:preReleaseBuild
:app:checkReleaseManifest
:app:preDebugBuild
:app:prepareComAndroidSupportSupportV132100Library UP-TO-DATE
:app:prepareComAndroidSupportSupportV42100Library UP-TO-DATE
:app:prepareComGoogleAndroidGmsPlayServices6171Library UP-TO-DATE
:app:prepareComSothreeSlidinguppanelLibrary202Library UP-TO-DATE
:app:prepareComUrbanairshipUrbanairshipLib510Library UP-TO-DATE
:app:prepareMeGrantlandAutofittextview011Library UP-TO-DATE
:app:prepareNetDanlewAndroidJoda240Library UP-TO-DATE
:app:prepareSeEmilsjolanderStickyScrollViewItems110Library UP-TO-DATE
:app:prepareSeEmilsjolanderStickylistheaders250Library 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
Note: <path_to_my_project>/app/src/main/java/com/xxx/xxx/fragments/MatchCenterFragment.java uses unchecked or unsafe operations.
Note: Recompile with -Xlint:unchecked for details.
:app:compileReleaseJava
:app:lintVitalRelease
:app:compileReleaseNdk
:app:proguardRelease
Warning: com.ooyala.android.player.WidevineLibPlayer: can't find superclass or interface com.widevine.drmapi.android.WVEventListener
( more com.ooyala.* warnings )
Warning: com.squareup.okhttp.internal.huc.HttpsURLConnectionImpl: can't find referenced method 'long getContentLengthLong()' in program class com.squareup.okhttp.internal.huc.HttpURLConnectionImpl
Warning: com.squareup.okhttp.internal.huc.HttpsURLConnectionImpl: can't find referenced method 'long getHeaderFieldLong(java.lang.String,long)' in program class com.squareup.okhttp.internal.huc.HttpURLConnectionImpl
Warning: com.squareup.okhttp.internal.huc.JavaApiConverter$CacheHttpsURLConnection: can't find referenced method 'long getContentLengthLong()' in program class com.squareup.okhttp.internal.huc.JavaApiConverter$CacheHttpURLConnection
Warning: com.squareup.okhttp.internal.huc.JavaApiConverter$CacheHttpsURLConnection: can't find referenced method 'long getHeaderFieldLong(java.lang.String,long)' in program class com.squareup.okhttp.internal.huc.JavaApiConverter$CacheHttpURLConnection
Warning: okio.DeflaterSink: can't find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
Warning: okio.Okio: can't find referenced class java.nio.file.Files
Warning: okio.Okio: can't find referenced class java.nio.file.Files
Warning: okio.Okio: can't find referenced class java.nio.file.Files
Warning: okio.Okio: can't find referenced class java.nio.file.Path
Warning: okio.Okio: can't find referenced class java.nio.file.OpenOption
Warning: okio.Okio: can't find referenced class java.nio.file.Path
Warning: okio.Okio: can't find referenced class java.nio.file.OpenOption
Warning: okio.Okio: can't find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
Warning: okio.Okio: can't find referenced class java.nio.file.Path
Warning: okio.Okio: can't find referenced class java.nio.file.OpenOption
Warning: okio.Okio: can't find referenced class java.nio.file.Path
Warning: okio.Okio: can't find referenced class java.nio.file.OpenOption
Warning: okio.Okio: can't find referenced class org.codehaus.mojo.animal_sniffer.IgnoreJRERequirement
Warning: there were 234 unresolved references to classes or interfaces.
         You may need to add missing library jars or update their versions.
         If your code works fine without the missing classes, you can suppress
         the warnings with '-dontwarn' options.
         (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedclass)
Warning: there were 4 unresolved references to program class members.
         Your input classes appear to be inconsistent.
         You may need to recompile the code.
         (http://proguard.sourceforge.net/manual/troubleshooting.html#unresolvedprogramclassmember)
:app:proguardRelease FAILED

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':app:proguardRelease'.
> java.io.IOException: Please correct the above warnings first.

* Try:
Run with --stacktrace option to get the stack trace. Run with --info or --debug option to get more log output.

BUILD FAILED

Total time: 14.674 secs
Please correct the above warnings first.
13:40:35: External task execution finished 'assembleRelease'.

Answer 1

Add this to ProGuard setting file(like proguard-rules.pro)

-dontwarn okio.**

Answer 2

I had to disable proguard with

minifyEnabled false

Not the best solution, but it works.

Answer 3

Add this to ProGuard setting file(like proguard-rules.pro)

-ignorewarnings 

Answer 4

I had the same problem with Gradle 1.1.0. It remembered some old class references which I have moved, and I couldn't build apk.

Try Build > Clean.

It helped me, and now I can build apk again.