Request method 'GET' is not supported - spring

Question

have two controllers, that should give Form (html +Thymeleaf) to Update entity and post new data, after redirect to List Entities;
My Controllers
#GetMapping ("/fromUpdate")
public String updateInstructor (Model model, Long instructorId) {
Instructor instructor = instructorService.loadInstructorById(instructorId);
model.addAttribute("instructor", instructor);
return "views/updateInstructor";
}
#PostMapping ("/update")
public String update (Instructor instructor) {
instructorService.updateInstructor(instructor);
return "redirect:/instructors/index";
}
Html form + Thymeleaf
<div class="col-md-6 offset-3 mt-3">
<form class="form-control" method="post"
th:action="#{/instructors/update}" th:object="${instructor}">
<div class="mb-3 mt-3">
<label class="form-label"> Instructor Id :</label>
<input type="number" name="instructorId" class="form-control"
th:value="${instructor.getInstructorId()}">
</div>
<div class="mb-3 mt-3">
<label for="firstName" class="form-label"> First Name :</label>
<input id="firstName" type="text" name="firstName" class="form-control"
th:value="${instructor.getInstructorFirstName()}">
</div>
<div class="mb-3 mt-3">
<label for ="lastName" class="form-label"> Last Name :</label>
<input id="lastName" type="text" name="lastName" class="form-control"
th:value="${instructor.getInstructorLastName()}">
</div>
<div class="mb-3 mt-3">
<label for="instructorSummary" class="form-label"> Summary :</label>
<input id="instructorSummary" type="text" name="instructorSummary" class="form-control"
th:value="${instructor.getInstructorSummary()}">
</div>
<div class="mb-3 mt-3" th:each ="course: ${instructor.getCourses()}">
<input name="courses" class="form-control"
th:value="${instructor.courses[courseStat.index].getCourseId()}">
</div>
<div class ="mb-3 mt-3">
<input name ="user" class="form-control" th:field="${instructor.user}">
</div>
<button type ="submit" class ="btn btn-primary"> Update </button>
</form>
</div>
When i load update form i give next exception
80 --- [nio-8071-exec-1] .w.s.m.s.DefaultHandlerExceptionResolver : Resolved [org.springframework.web.HttpRequestMethodNotSupportedException: Request method 'GET' is not supported]
Must say, when i set in first controller #GetMapping (value =/update) analogical Url with Post my form load with all data.
If you know where my problem, please say me, tnx!!!