Spring Thyme Leaf checking for global errors results in NPE - spring

Question

To display global errors created with Spring MVC with Thyme Leaf, I tried the example given at http://www.thymeleaf.org/doc/tutorials/2.1/thymeleafspring.html#global-errors:
That, is:
<div th:if="${#fields.hasGlobalErrors()}">
and
<ul th:if="${#fields.hasErrors('global')}">
and
<div th:if="${#fields.hasGlobalErrors()}">
When I add them to my HTML, the page won't even render, nevermind about submitting the form. All the examples result in:
org.springframework.web.util.NestedServletException: Request processing failed; nested exception is org.thymeleaf.exceptions.TemplateProcessingException: Exception evaluating SpringEL expression: "#fields.hasErrors('global')"
I tried this with v2.1.4 and v.2.1.3 and got the same error. Bug or am I doing something wrong?
Yes, the tags are all closed and properly formed. Yes, this code was within a form. Yes, all the other aspects of the form work without the global error check.
Here is a short version of broken HTML:
<form action="search.html" th:action="#{/auto/search}">
<p th:if="${#fields.hasErrors('global')}" th:errors="*{global}">
Incorrect date
</p>
<input type="text" th:field="${command.stockNumber}" />
<select th:field="*{command.startYear}">
<option value="" th:each="year : ${modelYears}" th:value="${year}"
th:text="${year}"></option>
</select>
</form>
And the controller..
#RequestMapping(value = "/auto/search", method = RequestMethod.POST)
public String search(#Validated
#ModelAttribute("command")
AutoSearchCommand autoSearchCommand
BindingResult result, Model model) {
return "search";
}

Answer 1

Solved:
th:object is needed in a tag preceding to the global error check. Unfortunately, this isn't mentioned in the Spring Thyme Leaf tutorial. Presumably, there's a default form name somewhere which I've overridden in my controller.
Adding the tag in results in this working html:
<form action="search.html" th:action="#{/auto/search}">
<div th:object="${command}" th:remove="tag">
<p th:if="${#fields.hasErrors('global')}" th:errors="*{global}">
Incorrect date
</p>
</div>
<input type="text" th:field="${command.stockNumber}" />
<select th:field="*{command.startYear}">
<option value="" th:each="year : ${modelYears}" th:value="${year}"
th:text="${year}"></option>
</select>
</form>
.. Where "command" is the name of the form bean in the controller.
This thread helped me figure it out.