It could be a certain module or plugin causing the error. I'd personally recommend re-installing the Prestashop Main files when you haven’t already. This is often also for security good reasons, so that you can’t make use of the title admin for a Listing folder name. You need to use https://addons.prestashop.com/de/seo-suchmaschinenranking-optimization/31857-automatische-google-rich-snippets-json-ld-opengraph-seo.html