Cannot delete a property 'Acad:Conductor.underground'; its class has objects 
Unsupport Schema modification; Cannot delete property 'Acad:Conductor.underground' 
Cannot add not-nullable property 'Acad:Conductor.Conductivity'; its class has objects 
Unsupported Schema modification; Cannot change identity properties for class 'Acad:Customer' from (First Name, Last Name) to (Last Name) 
Unsupported Schema modification; Cannot change property 'Acad:Customer.Credit Rating' to be writable 
Cannot change class type of class 'Acad:'Address'.  
