Trying to edit section on https://www.mediawiki.org/wiki/Wikidata_query_service/User_Manual#SPARQL_endpoint, I go to the section and click on "edit source". I get an error:
Cannot find section You tried to edit a section that does not exist. It may have been moved or deleted while you were viewing the page. Return to Wikidata query service/User Manual.
(Note: Temporary workaround: The easiest workaround, is to just edit the entire page. That way you can fix the individual problem(s). Any editor can do this, on non-protected original-language pages.)