Why i`m getting 400 Bad Request in Html Drop down list

Question

According to the requirement i developed following drop down and validation set to required. problem is when the field is Choose a category it gives 400 Bad request. what i want is This field is required in Html validation.

<div class="col-sm-10" id="category">
    <select required 
            class="form-control 
            input-sm" id="categorySelect"
            Тame="categorySelect">
        <option selected>Choose a category</option>
        <c:forEach var="cat" items="${categories}">
            <option value="${cat.catId}">
                ${cat.catName}
            </option>
        </c:forEach>
    </select>
</div>

Answer 1

Answer is just set the Value as none. see the following code segment.

<div class="col-sm-10" id="category">
    <select required class="form-control input-sm" id="categorySelect"
                                            name="categorySelect">
        <option value="" selected>Choose a category</option>
            <c:forEach var="cat" items="${categories}">
                <option value="${cat.catId}">${cat.catName}</option>
            </c:forEach>
    </select>