Update to Drupal 8.0.0 beta 14. For more information, see https://drupal.org/node/2544542

core/themes/classy/templates/form/datetime-wrapper.html.twig

@@ -24,7 +24,7 @@
 {% endif %}
 {{ content }}
 {% if errors %}
-  <div class="form-error-message">
+  <div class="form-item--error-message">
     <strong>{{ errors }}</strong>
   </div>
 {% endif %}

core/themes/classy/templates/form/fieldset.html.twig

@@ -40,7 +40,7 @@
   </legend>
   <div class="fieldset-wrapper">
     {% if errors %}
-      <div class="form-error-message">
+      <div class="form-item--error-message">
         <strong>{{ errors }}</strong>
       </div>
     {% endif %}

core/themes/classy/templates/form/form-element.html.twig

@@ -52,7 +52,7 @@
     'form-item-' ~ name|clean_class,
     title_display not in ['after', 'before'] ? 'form-no-label',
     disabled == 'disabled' ? 'form-disabled',
-    errors ? 'form-error',
+    errors ? 'form-item--error',
   ]
 %}
 {%
@@ -81,7 +81,7 @@
     {{ label }}
   {% endif %}
   {% if errors %}
-    <div class="form-error-message">
+    <div class="form-item--error-message">
       <strong>{{ errors }}</strong>
     </div>
   {% endif %}

core/themes/classy/templates/form/select.html.twig

@@ -10,4 +10,18 @@
  * @see template_preprocess_select()
  */
 #}
-<select{{ attributes }}>{{ options }}</select>
+{% spaceless %}
+  <select{{ attributes }}>
+    {% for option in options %}
+      {% if option.type == 'optgroup' %}
+        <optgroup label="{{ option.label }}">
+          {% for sub_option in option.options %}
+            <option value="{{ sub_option.value }}"{{ sub_option.selected ? ' selected="selected"' }}>{{ sub_option.label }}</option>
+          {% endfor %}
+        </optgroup>
+      {% elseif option.type == 'option' %}
+        <option value="{{ option.value }}"{{ option.selected ? ' selected="selected"' }}>{{ option.label }}</option>
+      {% endif %}
+    {% endfor %}
+  </select>
+{% endspaceless %}