Как исправить ошибку StreamCorruptedException: invalid type code: AC

Set<User> users = new HashSet<User>();
        try (ObjectInputStream objectInputStream = new ObjectInputStream(new FileInputStream(file))) {
 
            while (true) {
                User user = (User) objectInputStream.readObject();
                users.add(user);
            }
 
        } catch (IOException | ClassNotFoundException e) {
            e.printStackTrace();
        }

String username = readWithRetry(in, REGEX_NAME, INPUT, INCORRECT);

private static String newUser(Scanner scanner, String regex, String messageToShow, String errorMessage) {
        while (true) {
            System.out.println(messageToShow);
            String input = scanner.nextLine();
            if (input.matches(regex)) {
                return input;
            } else {
                System.out.println(errorMessage);
            }
        }
    }

private File writeInFile(String file, User user) {
        try (FileOutputStream fileOutputStream = new FileOutputStream(file, true)) {
            ObjectOutputStream objectOutputStream = new ObjectOutputStream(fileOutputStream);
            objectOutputStream.writeObject(user);
            objectOutputStream.close();
            System.out.printf("Serialized data is saved in users.txt");
 
        } catch (IOException e) {
            e.printStackTrace();
        }
        return new File(file);
    }