Gradle failed to sync with 'unable to find optional library'

Question

I had to reinstall my system and today I get this error in Android Studio when I try to sync with gradle:

Warning: Unable to find optional library: org.apach         


        

Answer 1

1. Copy "sdk\platforms\android-23\optional\org.apache.http.legacy.jar" to your app module libs directory, then add as library;
2. If you enable the proguard, please edit "proguard-rules.pro" to keep related classes or exception will occurred.

Answer 2

To save time 2 solutions are best and works for me.

Solution 1 :

open your android sdk manager and reinstall API 23 (remove and install again).

Solution 2 :

Download this file which contain optional.json file extract and move optional.json to :

C:\Users\\AppData\Local\Android\sdk\platforms\android-23\optional

Answer 3

Update your project gradle file to use gradle version 1.3.1.

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

Also try adding codehause repo.

repositories {
        mavenCentral()
        maven{
            url 'http://repository.codehaus.org'
        }
    }