It is likely you originally installed Breadcrumb NavXT back in the pre 5.3 days (before the default settings moved to Schema.org BreadcrumbList). You will need to ensure your wrapping code is updated for Schema.org BreadcrumbList and your breadcrumb templates are updated to be BreadcrumbList compliant.
See https://mtekk.us/archives/guides/how-to-implement-schema-org-breadcrumblist-with-breadcrumb-navxt/ for more information.
The plugin came with the Atelier theme ( atelier.swiftideas.com ) and all I did was to install a newer version of it. But I don’t remember having this issue in the past.
Also, is your script adding this somewhere in the footer of the product page:
<script type=”application/ld+json”>
… product schema
</script>
And I simply don’t get how a fix from 2015 would help my case. Isn’t your plugin plug-and-play sort of speak. Do I have to change my code in order to make it work ?
Actually even if I disable your plugin I still get that error, so it might not be from this… No idea what’s going on
The article from 2015 is from just before Breadcrumb NavXT officially moved to Schema.org’s BreadcrumbList. Migrating the templates from the old version to being Schema.org BreadcrumbList compliant isn’t a straight forward task if the user has modified any of them, hence the plugin leaves this as an exercise for the user. The article covers what has to be done to migrate your breadcrumb templates. Additionally, depending on the HTML surrounding your call to bcn_display() you may have to update that as well. The article covers this as well.
The application/ld+json most likely is not Breadcrumb NavXT, unless you are calling the bcn_display_json_ld() function, but even then it doesn’t deal with the product schema.
