"Flex Pages are required for Gantry to work!"

Hello,

after updates, the following has now appeared on the website - instead of the horizontal drop down menu: "Flex Pages are required for Gantry to work!"

( Gantry 5 Framework <small>v5.5.4</small>)

Any idea how to solve this?

thanks

update: when I turned it on in Gantry 5 settings ( Platform Settings) Debug Mode - Enabled, then in Layout - Navigation - Menu - setting, appears on the left :

Twig \ Error \ RuntimeError
An exception has been thrown during the rendering of a template ("Flex Pages are required for Gantry to
and bellow with a statement of about 100 reports

the first two are:

101 Twig\Error\RuntimeError

…/user/plugins/gantry5/admin/templates/forms/fields/menu/item.html.twig6

100 RuntimeException

…/user/plugins/gantry5/src/classes/Gantry/Framework/Menu.php109

and on the right:

/user/plugins/gantry5/admin/templates/forms/fields/menu/item.html.twig

{% extends 'forms/fields/select/selectize.html.twig' %}

{% block options %}
    {{ parent() }}
    {% if gantry.menu is not null %}
        {% for group, items in gantry.menu.getGroupedItems() %}
            {% if items|length %}
            <optgroup label="{{ group|capitalize }}">
            {% for key, item in items %}
            <option
                    {# required attribute structures #}
                    {% if key == value %}selected="selected"{% endif %}
                    value="{{ key }}"
                    {# non-gloval attribute structures #}
                    {% if field.options.disabled in ['on', 'true', 1] %}disabled="disabled"{% endif %}
                    >{{ item.spacing|raw }}{{ item.label }}</option>
            {% endfor %}
            </optgroup>
            {% endif %}
        {% endfor %}
    {% endif %}
{% endblock %}

Arguments

"An exception has been thrown during the rendering of a template ("Flex Pages are required for Gantry to work!")."