spring and thymeleaf form-select

I have a problem with selector in thymeleaf.

I have this code:

public class categoria {

private String categoria;

public String getCategoria() {
    return categoria;
}

public void setCategoria(String categoria) {
    this.categoria = categoria;
}


public void addViewControllers(ViewControllerRegistry registry) {
    registry.addViewController("/home").setViewName("home");
    registry.addViewController("/").setViewName("home");
    registry.addViewController("/hello").setViewName("hello");
    registry.addViewController("/login").setViewName("login");
    registry.addViewController("/combinacionProductos").setViewName("combinacionProductos");
}

and this is my html

<form id="categoriaForm" th:action="@{/provincias}" th:object="${categoria}" method="post">
<label>Seleccionar Categoria:</label>
 <!-- Use th:field to select *{paymentMethod} -->
 <br/>
 <select th:field="*{categorias}">
        <option th:each="categoria : *{categorias}"
                th:value="${categoria}"
                th:text="${categoria}">
                Categoria
        </option>
 </select>
 </form>

when I execute this, i recibe the next output:

In browser:

Error during execution of processor 'org.thymeleaf.spring4.processor.attr.SpringSelectFieldAttrProcessor'

In logger:

java.lang.IllegalStateException: Neither BindingResult nor plain target object for bean name 'categoria' available as request attribute at org.springframework.web.servlet.support.BindStatus.(BindStatus.java:144) at org.thymeleaf.spring4.util.FieldUtils.getBindStatusFromParsedExpression(FieldUtils.java:348) at org.thymeleaf.spring4.util.FieldUtils.getBindStatus(FieldUtils.java:288) at org.thymeleaf.spring4.util.FieldUtils.getBindStatus(FieldUtils.java:260) at org.thymeleaf.spring4.processor.attr.AbstractSpringFieldAttrProcessor.processAttribute(AbstractSpringFieldAttrProcessor.java:97) at org.thymeleaf.processor.attr.AbstractAttrProcessor.doProcess(AbstractAttrProcessor.java:87) at org.thymeleaf.processor.AbstractProcessor.process(AbstractProcessor.java:212) at org.thymeleaf.dom.Node.applyNextProcessor(Node.java:1016) at org.thymeleaf.dom.Node.processNode(Node.java:971) at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:672) at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:655) at org.thymeleaf.dom.Node.processNode(Node.java:990) at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:672) at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:655) at org.thymeleaf.dom.Node.processNode(Node.java:990) at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:672) at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:655) at org.thymeleaf.dom.Node.processNode(Node.java:990) at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:672) at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:655) at org.thymeleaf.dom.Node.processNode(Node.java:990) at org.thymeleaf.dom.NestableNode.computeNextChild(NestableNode.java:672) at org.thymeleaf.dom.NestableNode.doAdditionalProcess(NestableNode.java:655) at org.thymeleaf.dom.Node.processNode(Node.java:990) at org.thymeleaf.dom.Document.process(Document.java:93) at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1155) at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1060) at org.thymeleaf.TemplateEngine.process(TemplateEngine.java:1011) at org.thymeleaf.spring4.view.ThymeleafView.renderFragment(ThymeleafView.java:335) at org.thymeleaf.spring4.view.ThymeleafView.render(ThymeleafView.java:190) at org.springframework.web.servlet.DispatcherServlet.render(DispatcherServlet.java:1221) at org.springframework.web.servlet.DispatcherServlet.processDispatchResult(DispatcherServlet.java:1005) at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:952) at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:870) at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:961) at org.springframework.web.servlet.FrameworkServlet.doGet(FrameworkServlet.java:852) at javax.servlet.http.HttpServlet.service(HttpServlet.java:620) at org.springframework.web.servlet.FrameworkServlet.service(FrameworkServlet.java:837) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:303) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.web.filter.HiddenHttpMethodFilter.doFilterInternal(HiddenHttpMethodFilter.java:77) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:330) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.invoke(FilterSecurityInterceptor.java:118) at org.springframework.security.web.access.intercept.FilterSecurityInterceptor.doFilter(FilterSecurityInterceptor.java:84) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.access.ExceptionTranslationFilter.doFilter(ExceptionTranslationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.session.SessionManagementFilter.doFilter(SessionManagementFilter.java:103) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AnonymousAuthenticationFilter.doFilter(AnonymousAuthenticationFilter.java:113) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.servletapi.SecurityContextHolderAwareRequestFilter.doFilter(SecurityContextHolderAwareRequestFilter.java:154) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.savedrequest.RequestCacheAwareFilter.doFilter(RequestCacheAwareFilter.java:45) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.AbstractAuthenticationProcessingFilter.doFilter(AbstractAuthenticationProcessingFilter.java:199) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.authentication.logout.LogoutFilter.doFilter(LogoutFilter.java:110) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.csrf.CsrfFilter.doFilterInternal(CsrfFilter.java:85) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.header.HeaderWriterFilter.doFilterInternal(HeaderWriterFilter.java:57) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.SecurityContextPersistenceFilter.doFilter(SecurityContextPersistenceFilter.java:87) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.context.request.async.WebAsyncManagerIntegrationFilter.doFilterInternal(WebAsyncManagerIntegrationFilter.java:50) at org.springframework.web.filter.OncePerRequestFilter.doFilter(OncePerRequestFilter.java:107) at org.springframework.security.web.FilterChainProxy$VirtualFilterChain.doFilter(FilterChainProxy.java:342) at org.springframework.security.web.FilterChainProxy.doFilterInternal(FilterChainProxy.java:192) at org.springframework.security.web.FilterChainProxy.doFilter(FilterChainProxy.java:160) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:241) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:208) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:220) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:122) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:503) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:170) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:103) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:116) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:421) at org.apache.coyote.http11.AbstractHttp11Processor.process(AbstractHttp11Processor.java:1070) at org.apache.coyote.AbstractProtocol$AbstractConnectionHandler.process(AbstractProtocol.java:611) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1736) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.run(NioEndpoint.java:1695) at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142) at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:61) at java.lang.Thread.run(Thread.java:745)

I also probe add this:

@RequestMapping("/provincias")
public ModelMap form(ModelMap model) {
    model.addAttribute("categoria", ProvinciasController.provincias());
    return model;
}

But doesnt work. What is the problem?

Thank you!