Steps to replicate the issue (include links if applicable):

• Opt-in new Parsoid wikitext parser
• Visit https://it.wikipedia.org/wiki/Discussioni_progetto:Biografie/Errori#Imperatore_romano_nel_Bio
• Click [edit source] (the button links to URL: https://it.wikipedia.org/w/index.php?title=Discussioni_progetto:Biografie/Errori&action=edit&section=224 )

What happens?:
Error "You tried to edit a section that does not exist. It may have been moved or deleted while you were viewing the page." is displayed

What should have happened instead?:
Using the legacy parser the edit source URL is https://it.wikipedia.org/w/index.php?title=Discussioni_progetto:Biografie/Errori&action=edit&section=74 (it correctly opens the edit interface)