I and my friend have project files connected to dropbox. So code are the same. Then, when I execute Code: NSEntityDescription *entity = [NSEntityDescription entityForName:@"Business" inManagedObjectContext:[BNUtilitiesQuick managedObjectContext]]; I got something. That same code set entity to nil in my friends' computer. My friend manage to run the code anyway with something they called profile. Then it works. But then it fails again if run again without profile but the error change: The BadgerNew.xcdatamodeld that's used to create the managedObject already changed. My team have reset the IPhone simulator and deleted the application from the IPhone simulator so that the whole thing is created new again. Doesn't work.