error: cannot find symbol variable EXTRA_MESSAGE in Android Studio

include this in your main activity class
public final static String EXTRA_MESSAGE = "com.example.myfirstapp.MESSAGE";

It's already there. I had the same issue. In the item 'Build an Intent' it's included. Not in the previous step. That's the problem with the copy and paste thing. Part of the learning proces

The general causes for a Cannot find symbol error are things like:

• Incorrect spelling.
• Wrong case. Halo is different from halo.
• Improper use of acceptable identifier values (letters, numbers,
  underscore, dollar sign), my-class is not the same as myclass.
• No variable declaration or variable is outside of the scope you are
  referencing it in.

Eldo

hola disculpa mi ignorancia no entiendo, cual es el problema de copiar y pegar?