Issue: Database Error: INSERT INTO `xf_data_registry` (`data_key`, `data_value`) VALUES ('vw_nodetypes'

The error message "Mysqli statement execute error : Prepared statement needs to be re-prepared" appears to either be a bug in MySQL < 5.7 related to executing MySQL statements while backup processes are dumping the same table (make sure your version is more recent) or a bug in Zend Framework's Database connection (XenForo uses this library, but likely does not use a version that includes the "temporary fix").

I suspect this is a similar error to "MySQL went away", which we frequently see in our logs (nearly every morning at the same minute) when the database is dumping.

There is nothing wrong with the MySQL statements themselves, so this is not a bug in VaultWiki. This is because while your database is backing up, all tables are locked, so connections/writes may fail.