Why does "CommandInvokationFailure: Unable to convert classes into dex format" occur when building in unity3d?

Question

Android

When building for Android, the following error occurs
CommandInvokationFailure: Unable to convert classes into dex format.
C:/Program Files/Java/jdk1.7.0_79\bin\java.exe -Xmx2048M -Dcom.android.sdkmanager.toolsdir="C:/Users/Admin/AppData/Local/Android/android-sdk\tools" - Dfile.encoding=UTF8 -jar "C:\Program Files\Unity\Editor\Data\PlaybackEngines\AndroidPlayer/Tools\sdktools.jar" -

Answer 1

answers.unity3d.com/questions/765961/multiple-plug...