Warning:Unable to find optional library: org.apache.http.legacy

In lollipop development the library containing http protocols wont work, for that you have add this line to the gradle.

useLibrary 'org.apache.http.legacy'

and then sync it



Warning:Unable to find optional library: org.apache.http.legacy


guess, the easier way to solve this issue without having to reinstall the SDK is to create a file called optional.json in <sdk-path>\platforms\android-23\optional\ directory with the following content:

[
  {
    "name": "org.apache.http.legacy",
    "jar": "org.apache.http.legacy.jar",
    "manifest": false
  }
]
It solved the problem for me.

EDIT: Information taken from @domoch's answer below on how to locate your SDK location

To Locate your Android SDK's Location
Go to Android Studio Settings -> Appearence & Behavior -> System Settings and look for Android SDK Location. In Windows, it usually would be pointing to C:\Users\<username>\AppData\Local\Android\sdk.