Due to a bug, XML converters in the contentserver had to be configured with a duplicate sql.store.convert prefix, like

sql.store.convert.sql.store.convert.MyContentType.myXmlProperty=example.org.MyConverter

This has been fixed now, so XML converters must be configured as intended with a single prefix now:

sql.store.convert.MyContentType.myXmlProperty=example.org.MyConverter

(CMS-26006)