Fatal Error: Java.Lang.illegalstateacception: Expected BEGIN_OBJECT but was STRING at line 1 column 1.

At First it kept saying Couldnt Unpack Natives Now its saying Fatal Error and it told me to contact Mojang It Sayed: Java.Lang.illegalstateacception: Expected BEGIN_OBJECT but was STRING at line 1 column 1.

Please Help Me I like to Play minecraft and hoping to start my own Youtube Channel ))!