In my project I can’t access the autoload script, and there is no node named root in the project tree, just the normal scene nodes. I’ve created and activated one singleton named GlobalVariables following the Singletons (Autoload) tutorial but is missing. I don’t know what can be wrong.
Accessing Singleton not from _ready() function is a common thing that will return you a null reference. GlobalVariables should be available from any place if used in _ready()
you can access you singleton using get_node('/root/GlobalVariables')