Hi everyone. I have created an application that manages groups of contacts, some customers complain that they cannot insert the contacts in a group, and I have verified that this error is obtained: "Updated Record Does Not Exists" e "CNDomainError error 2" I have looked for a possible cause but I have not found anything, this is the code that I run when I add a contact in a group: func addContactToGroup (group: CNGroup, contactIdentifier: String) throws { 				 let saveRequest = CNSaveRequest () 				 let contact = (try? self.store.unifiedContact (withIdentifier: contactIdentifier, keysToFetch: kToFetch)) ?? nil 				 if contact! = nil { 						 saveRequest.addMember (contact !, to: group) 						 try store.execute (saveRequest) 				 } 		 } The strange thing is that on most installations it works regularly. Anyone know what it can depend on?