Fix: breadcrumb in FileAdmin

flask_admin/templates/bootstrap4/admin/file/list.html

@@ -4,21 +4,23 @@
 
 {% block body %}
     {% block breadcrums %}
-    <ul class="breadcrumb">
-        <li>
+      <nav area-label="breadcrumb">
+        <ol class="breadcrumb">
+          <li class="breadcrumb-item">
             <a href="{{ get_dir_url('.index_view', path=None) }}">{{ _gettext('Root') }}</a>
           </li>
           {% for name, path in breadcrumbs[:-1] %}
-        <li>
+          <li class="breadcrumb-item">
             <a href="{{ get_dir_url('.index_view', path=path) }}">{{ name }}</a>
           </li>
           {% endfor %}
           {% if breadcrumbs %}
-        <li>
+          <li class="breadcrumb-item">
             <a href="{{ get_dir_url('.index_view', path=breadcrumbs[-1][1]) }}">{{ breadcrumbs[-1][0] }}</a>
           </li>
         {% endif %}
-    </ul>
+        </ol>
+      </nav>
     {% endblock %}
 
     {% block file_list_table %}