Key "html" for sequence/mapping with keys "label, url" does not exist.

[thisisjamessmith]

I've upgraded a site from Craft 4 to 5 and get this error when clicking on a saved submission in the CP:

Key "html" for sequence/mapping with keys "label, url" does not exist.
...in /vendor/craftcms/cms/src/templates/_layouts/components/crumbs.twig

Anyone else?

[thisisjamessmith]

It looks like this extension's template at vendor/hybridinteractive/craft-contact-form-extensions/src/templates/submissions/_show.twig is expecting each submission to have a defined subject, but mine have none (the subject text comes from the Contact Form plugin instead). Adding a default in there fixes it:

https://github.com/hybridinteractive/craft-contact-form-extensions/blob/v5/src/templates/submissions/_show.twig#L13

{% if crumbs is not defined %}
    {% if submission %}
        {% set crumbs = [
            { label: craft.contactFormExtensions.name, url: url('contact-form-extensions') },
            { label: submission.subject ?? 'No subject', url: '' }
        ] %}

    {% else %}
        {% set crumbs = [
            { label: craft.contactFormExtensions.name, url: url('contact-form-extensions') }
        ] %}
    {% endif %}
{% endif %}