How to edit image attribute in Spring MVC and Hibernate

I need to edit a form that also has an image attribute of type blob. Whenever I edit the form and submit it, it shows me the error page catching a java.lang.NullPointerException but the data is actually being persisted in the database and it is also showing in the view. I need the submit button to redirect me to another page and I cannot achieve that.

This is my edit form method:

@Transactional
    @RequestMapping(value = "/update/{id}", method = RequestMethod.POST)
    public String updateEmployeeProfile(@PathVariable("id")int id, @RequestParam("profilePicture") MultipartFile file,
                                        @RequestParam("name") String name,
                                        @RequestParam("birthDate") String birthDate,
                                        @RequestParam("address") String address,
                                        @RequestParam("phone") String phone,
                                        @RequestParam("email") String email,
                                        @RequestParam("designation") String designation,
                                        @RequestParam("jobDescription") String jobDescription){

        employee employee = em.find(com.techflakes.advocatoree.model.employee.class, id);
        SimpleDateFormat sdf = new SimpleDateFormat("dd-MM-yyyy");
        try {
            employee.setName(name);
            employee.setProfilePicture(file.getBytes());
            employee.setAddress(address);
            employee.setBirthDate(sdf.parse(birthDate));
            employee.setDesignation(designation);
            employee.setEmail(email);
            employee.setJobDescription(jobDescription);
            employee.setPhone(phone);
            if (employee.getCurrent().equals("Yes")) {
                employee.setCurrentemployee(true);
            } else {
                employee.setCurrentemployee(false);
            }
        }catch (Exception ex)
        {
            System.out.println(ex);
            return "redirect:/advocatoree/error";
        }
        em.persist(employee);
        return "redirect:/advocatoree/manageEmployee/browseEmployees";
    }

What should I do?