SQL> EXECUTE DBMS_SPACE_ADMIN.TABLESPACE_MIGRATE_TO_LOCAL('SYSTEM');
Before performing the migration the following conditions must be met:
The database has a default temporary tablespace that is not
There are no rollback segments in the dictionary-managed tablespace.
There is at least one online rollback segment in a locally managed tablespace, or if using automatic undo management, an undo tablespace is online.
All tablespaces other than the tablespace containing the undo space (that is, the tablespace containing the rollback segment or the undo tablespace) are in read-only mode.
The system is in restricted mode.
There is a cold backup of the database.
All of these conditions, except for the cold backup, are enforced by the
SYSTEMtablespace is migrated to locally managed, any dictionary-managed tablespaces in the database cannot be made read/write. If you want to be able to use the dictionary-managed tablespaces in read/write mode, then Oracle recommends that you first migrate these tablespaces to locally managed before migrating the