Java post submission occasionally get no value, do you have a friend who encounters the same thing?

make a POST submission on the JSP page. Action occasionally fails to get a value. Project framework SSM
data relationship student studentInfo
student entity contains studentInfo entity, one-to-one relationship
JSP input tag:

<form:input path="sfzhm"/>
<form:input path="studentInfo.email"/>

action:

@RequestMapping(value = "save", method = RequestMethod.POST)
public String save(Student student) throws Exception {
    StudentInfo studentInfo = student.getStudentInfo();
    studentService.studentUpdate(student);
    studentInfoService.studentUpdate(studentInfo);
    return "redirect: /student";
}

action entity printing time is not null
service directly calls dao
print sql:

UPDATE student SET syszd = ?, zzmm = ?, mobile = ?, update_date = ? WHERE id = ? 
:null, null, null, 2018-09-15 01:11:08.054(Timestamp), null

in fact, you can see from action that the parameter is directly empty, debug. Production environment tests can not be tested, but some users will have this kind of question, go to ask, some users are good to change the computer.

the project currently has 8000 users and has successfully submitted more than 6000 people. There are also some people who do not operate. The number of people who can"t submit it every day is less than two digits. There is no test in the production environment that cannot be submitted.

A total of 30 fields are submitted on the page

I"d like to ask you to see if anyone knows why this might have been taken (maybe the underlying bug? ), how to solve the problem. How to reproduce this kind of problem. Thank you!