In version 3.1606 we made some internal technical improvements to Asset Bank as part of which we removed the components.xconf file.
Because components.xconf is not being used any more the settings Asset Bank uses to connect to the database need to be stored somewhere else, so they are now stored in a new file: <asset-bank>/WEB-INF/classes/database-local.properties.
The Asset Bank updater automatically copies the settings from components.xconf to database.properties when you upgrade so no manual steps are necessary when upgrading.
However, you do need to be aware that newer versions of Asset Bank store database settings in a different place from older ones, so if you want to change the database settings you need to edit a different file depending on which version of Asset Bank you are using. A simple rule of thumb is to edit <asset-bank>/WEB-INF/classes/database-local.properties if it exists, and if not to edit <asset-bank>/WEB-INF/components.xconf.