thymeleaf-spring | Thymeleaf integration module for Spring | Model View Controller library

Most likely your forgot to add user object to Model in a controller method that landed you on this form page. To make sure that doesn't happen best is to just add model attributing method to controller that always takes care of this:

The exception cause shows what is wrong:

Malformed markup: Attribute "lang" appears more than once in element

You have this in your HTML:

You are using spring boot parent version 2.5.1 that is why it is downloading log4j 2.14.1 by default during the build. There are no other conflicts with any of the other dependencies in your pom.xml so try the latest spring boot starter-parent version.

According to the described setup, particularly:

Your CurrencyExchange_Logic class has two constructors: the required args constructor, which has parameters corresponding to the 3 final fields, and the all args constructor, with parameters corresponding to those 3 fields as well as start and end.

When you only have one constructor defined, Spring knows how to implicitly choose it for injection. However, when you have more than one, you have to tell it which one you want it to use, using the @Autowired or @Inject annotation.

I would guess you want Spring to use the required args constructor, as I doubt Spring has any way of knowing how to resolve the start or end fields. This can be done in lombok (@RequiredArgsConstructor(onConstructor_ = @Autowired)), or by just explicitly writing the constructor yourself and annotating it. Note you could also get rid of the all args constructor, if you don't need it, and Spring's implicit constructor injection should "just work."

I think that what happens here is the following:

Your logout form is managed by Thymeleaf which means that under the hood Thymeleaf will try to create a hidden field with the CSRF token inside. This normally works and it requires existing or new session.

The problem is that Thymeleaf is designed to minimize latencies by producing template output as your template is being processed. Thus when a page is longer in size (as it is in your case) by the time when the engine reaches your logout

So I'm not sure what exactly to advise you here. Maybe try to output the logout button earlier in your templates or optionally try to eagerly initialize the CSRF token. This setting in HttpSecurity will possibly do it:

According to your ss you have named the template as field-view.html but in controller you are returning view-fields.

Your code :

Hey finally I found solution:

Step 1

I put the page and the layout in the same folder:

I resolved it. The problem is Tomcat 10 does not work with Spring 5. So, I will use Tomcat 9.