XMB is mandatory in 12c
Hi,
Oracle XML DB is now a mandatory component of Oracle Database: you cannot uninstall it, and there is no option not to include it when you create Oracle Database.
It is automatically installed when you create a new database version 12.1.0.1. XDB's objects will be installed in tablespace SYSAUX.
If Oracle XML DB is not already installed in your database prior to an upgrade to Oracle Database 12.1.0.1 or later, then it is automatically installed in tablespace SYSAUX during the upgrade.
If Oracle XML DB has thus been automatically installed, and if you want to use Oracle XML DB, then, after the upgrade operation, you must set the database compatibility to at least 12.1.0.1.