A local variable named 'var' cannot be declared in this scope because it would give a different meaning to 'var', which is already used in a 'parent or current' scope to denote something else
A variable declaration hides another declaration that would otherwise be in scope. Rename the variable that is declared on the line that generated CS0136.
The following sample generates CS0136:
namespace x { public class a { public static void Main() { int i = 0; { char i = 'a'; // CS0136, hides int i } i++; } } }