Twig Runtime Error – Twig\Error\RuntimeError Key "html" for sequence/mapping with keys "label, url" does not exist.

[matthewstick]

Migrated from Craft 3 to 4 to 5. We get a "Twig\Error\RuntimeError Key" error when trying to view an entry that is saved to the database - i.e.e a deep link URL here:

https://domain.com/admin/contact-form-extensions/submissions/12345

This only happens if in dev mode. If in production mode, the form loads fine.

Running:
Contact Form: 3.1.0
Contact Form Extensions: 5.0.0
Craft CMS Pro: 5.8.0

Here's some context that may help:

Twig Runtime Error – Twig\Error\RuntimeError
Key "html" for sequence/mapping with keys "label, url" does not exist.
1. in /var/www/html/craft/vendor/craftcms/cms/src/templates/_layouts/components/crumbs.twigat line 36                aria: {
                  label: crumb.ariaLabel ?? false,
                },
              } %}
                {% if crumb.icon is defined %}
                  {% set iconAltText = crumb.iconAltText ?? null %}
                  <span class="cp-icon puny">{{ iconSvg(crumb.icon, altText: iconAltText) }}</span>
                {% endif %}
 
                <span>{{ crumb.label ?? crumb.html|raw }}</span>
              {% endtag %}
 
              {% if hasMenuItems %}
                {% set menuId = crumb.id is defined ? "#{crumb.id}-menu" : "crumb-menu#{random()}" %}
                {% set menuLabel = crumb.menu.label ?? null %}
                {{ tag('button', {
                  class: ['btn', 'menubtn'],
                  type: 'button',
                  aria: {
2. in /var/www/html/craft/vendor/craftcms/cms/src/helpers/Template.php at line 148– Twig\Extension\CoreExtension::getAttribute(craft\web\twig\Environment, Twig\Source, ['label' => null, 'url' => ''], 'html', ...)

[patrikkaprinay]

The error is probably due to the missing subject value. Try adding:
<input type="hidden" name="subject" value="New Message">
into the form.

[matthewstick]

Thanks. This is in the control panel, not in any front end logic. So we can't change it.