Remove role="form" on a form element.

Role Form should be use on a region of the document that  represents a collection of form-associated elements.
<div role=”form”></div> GOOD
<form role=”form”></form> BAD

templates/default/register.html

@@ -15,7 +15,7 @@
 
             <h1 id="main-label" class="page-header">{intl l="Create New Account"}</h1>
             {form name="thelia.front.customer.create"}
-            <form id="form-register" class="form-horizontal" action="{url path="/register"}" method="post" role="form">
+            <form id="form-register" class="form-horizontal" action="{url path="/register"}" method="post">
                 {form_field form=$form field='success_url'}
                     <input type="hidden" name="{$name}" value="{url path="/account"}" /> {* the url the user is redirected to on registration success *}
                 {/form_field}