Whenever i try to update anything in a category being: description, design, seo etc. i get greeted with this nice error:
Element 'referenceBlock': This element is not expected. Expected is one of ( referenceContainer, container, update, move, head, body ).Line: 1
This has only just started appearing for an unknown reason. I havent updated magento recently since it stopped working. And am on 2.2.5 running php 7.1.