Update operation is not performing -Resolved [org.springframework.web.HttpRequestMethodNotSupportedException: Request method 'POST' not supported]

I'm trying to develop an application in spring boot + thymeleaf, and I'm able to retrieve the logged in user details in the profile tab from the MySQL database, but when I try to change one or two field details (update) and hit the update button it is showing me an error message - Fri Sep 04 20:39:47 IST 2020
There was an unexpected error (type=Method Not Allowed, status=405).
Request method 'POST' not supported

see my controller code (I'm using @RestController annotated on top of the class)-

@RequestMapping(value = "/profile", method = RequestMethod.PUT)
	public ModelAndView updateProfile(@ModelAttribute Customer customer, HttpSession session) {
		
		ModelAndView model = new ModelAndView();
		
		Customer exist = cRepo.findByCustEmail(customer.getCustEmail());

		if(exist != null) {
			if(exist.getCustEmail().equals(session.getAttribute("emailsession"))) {
				
				cRepo.save(customer);
				model.addObject("msg", "User Details has been successfully updated!!");
				model.setViewName("profile");
			}
				
		}else {
			
			model.addObject("exist", "Please enter correct email address!");
			String email = (String) session.getAttribute("emailsession");
			Customer cust = cRepo.findByCustEmail(email);
			model.addObject("customer", cust);
			model.setViewName("profile");
			
		}
		
		return model;
	}

Thymleaf code (html) -

<div align="center" class="alert alert-success" th:if="${msg}" th:utext="${msg}"></div>
<div align="center" class="alert alert-danger" th:if="${exist}" th:utext="${exist}"></div>

	<!-- Modal HTML -->
<div id="myModal">
	<div class="modal-dialog modal-login">
		<div class="modal-content">
			<div class="modal-header">				
				<h4 class="modal-title">Profile Details</h4>
			
			</div>
			<div class="modal-body">
				<form name="myForm" th:action="@{/profile}" th:object="${customer}" method="post">
					
					<div class="form-group">
						<i class="fa fa-id-card"></i> 
						<input name="id" type="text" class="form-control" placeholder="Enter Id" th:field="${customer.custId}" disabled="true" required="required" />
					</div>
					<div class="form-group">
						<i class="fa fa-user"></i>
						<input name="name" type="text" class="form-control" placeholder="Enter Name" th:field="${customer.custName}"  required="required" />
					</div>
					<div class="form-group">
						<i class="fa fa-envelope"></i> 
						<input name="email" type="email" class="form-control" placeholder="Enter Email" th:field="${customer.custEmail}" required="required" />
					</div>
					<div class="form-group">
						<i class="fa fa-lock"></i>
						<input name="password" type="text" class="form-control" placeholder="Enter Password" th:field="${customer.custPassword}" required="required" />					
					</div>
					<div class="form-group">
						<input type="submit" class="btn btn-primary btn-block btn-lg" value="Update" />
					</div>
				</form>
			</div>
		</div>
	</div>
</div>     

I want when user login and visit he/she should be able to check his/her profile(which I'm able to do working code) and when the user wants to update few fields(1-2 based on choice) and hit update he/she should be able to update the details (not create new user or record) because when I use @Controller on top of class then this code work and create new user instead update.

Your controller is annotated with @RequestMapping(value = "/profile", method = RequestMethod.PUT) which makes it a PUT endpoint. However, your request is clearly a POST. If we look at your html form it contains method="post". HTML forms only support GET and POST as valid methods so you need to update your endpoint to be a POST endpoint.

tldr;

RequestMapping(value = "/profile", method = RequestMethod.PUT)

to

RequestMapping(value = "/profile", method = RequestMethod.POST) 

You request mapping in <form> is POST but Controller has set to accept request as PUT.

<form name="myForm" th:action="@{/profile}" th:object="${customer}" **method="post"**>


@RequestMapping(value = "/profile", method = **RequestMethod.PUT**) 

Just keep these in similar way both should be same.

Please check what I find and resolve this.

@RequestMapping(value = "/profile" ,method = RequestMethod.POST)
	public ModelAndView updateProfile(@ModelAttribute Customer customer, HttpSession session) {
		
		ModelAndView model = new ModelAndView();
		
		Customer exist = cRepo.findByCustEmail(customer.getCustEmail());

		if(exist != null) {
			if(exist.getCustEmail().equals(session.getAttribute("emailsession"))) {
				
				**exist.setCustId(exist.getCustId());
				exist.setCustName(customer.getCustName());
				exist.setCustEmail(customer.getCustEmail());
				exist.setCustPassword(customer.getCustPassword());**
				
				cRepo.save(exist);
				model.addObject("msg", "User Details has been successfully updated!!");
				
				model.addObject("customer", exist);
				model.setViewName("profile");
			}
				
		}else {
			
			model.addObject("exist", "Please enter correct email address!");
			String email = (String) session.getAttribute("emailsession");
			Customer cust = cRepo.findByCustEmail(email);
			model.addObject("customer", cust);
			model.setViewName("profile");
			
		}
		
		return model;
	}