Most (all but the DB2 script) of the database upgrade scripts that are version 25 identify themselves as version 24, causing Openfire to think that a new database script needs to be installed at every boot. This causes a new index to be created, repeatedly. As the index is created by name, I am assuming that this either overwrites a previous index, or fails.
This affects updating users only. The installation script that is used for new installations updates the version number correctly.