It could be a particular module or plugin triggering the error. I'd personally advise re-installing the Prestashop core files if you haven’t already. That is also for security good reasons, so that you can’t make use of the name admin to be a directory folder name. You can use almost https://addons.prestashop.com/nl/seo-zoekmachineoptimalisatie-vermelding/31857-automatische-google-rich-snippets-json-ld-opengraph-seo.html