The Page Preview feature (also called 'Popups') gives a thumbnail representation of a page when the reader hovers the mouse over a hyperlink to a wiki article. WMF took this feature out of the (internal) MediaWiki REST API and created a separate Wikimedia REST API called RESTBase PCS (Page Content Service) which is only available to WMF projects - not third-party wikis.

Because of this, independent wikis have started to demonstrate a loss of functionality going back to ~2022 and MediaWiki 1.38

In 2024, using MediaWiki 1.39 the Text Extracts extension returns the output of the Parser Limit Reporting HTML comment. Even if you turn off Parser Limit Reporting, there is still nominal output and it's the only thing "found" by the Text Extracts extension. (details below)

For most links, Text Extracts generates a misleading error message "There was an issue displaying this preview" when it really means that the extract is empty.

The endpoint in PCS needed for Page Previews is the 'page summary'.

• RfC: OpenGraph descriptions in wiki pages 2019
• Add hover-card like summary (og:description) to open graph meta data printing plain summary and headline property in the SameAs schema 2016
• [EPIC] Port page summary endpoint to MW 2024
• TextExtracts extension: Code stewardship review aka Text Extracts is unmaintained. 2020
• RESTBase
• RESTBase deprecation 2019
• RESTBase gerrit repo
• RESTBase github clone