When you are using the DBUA or performing a manual upgrade, you will need both versions of the database present to complete the operation.
Typically, you will be installing Oracle 12c into a new ORACLE_HOME on the existing server.
The DBUA can be started directly from the Oracle Universal Installer (OUI) during installation, or separately after the software installation is complete.
Make sure the database is started and run the database upgrade assistant.
This article does not include any references to pluggable databases, as in most cases the upgrade to 12c is a prerequisite of conversion to pluggable databases.
Direct upgrades to 12c are possible from existing databases with versions 10.2.0.5 , 188.8.131.52 , or release 184.108.40.206 .
If you would like to use DBUA to upgrade a multitenant container database, the Complete Checklist for Upgrading Oracle 12.2 Container Database (CDB) to Oracle Database 12c Release 2 (12.2) using DBUA (Doc ID 2240413.1) provides a check list for review.
If you are planning a manual upgrade of a non-CDB database, the Complete Checklist for Manual Upgrades to Non-CDB Oracle Database 12c Release 2 (Doc ID 2173141.1) provides a check list for review prior to performing a manual upgrade.
For instance, we learn what’s required to upgrade an Oracle 10g/11g database to 12c, and how we can verify successful upgrade.
The down sides of this approach are it is much slower, and it requires enough disk space to hold two copies of the database and the export dump file.
The "$ORACLE_HOME/rdbms/admin/utlu111i.sql" script performs pre-update validation checks on an existing instance.
Check the environment with: $ env | grep ORACLE_HOME $ env | grep ORACLE_BASE $ env | grep PATH (this should no longer contain a reference to 112_64) Run the SBP post-installation instructions as described in the corresponding SBP README set IHRDBMS=/oracle/SID/12102 set OHRDBMS=/oracle/SID/121 set SBPFUSER=/sbin/fuser env ORACLE_HOME=$OHRDBMS $OHRDBMS/sapbundle/catsbp - Create the symbolic link for BR*Tools 7.40: cd /oracle/client If the link or directory 11x_64 already exists, rename it, as in this example: mv 11x_64 11x_64_save Create the symbolic link: ln -s /oracle/client/12x /oracle/client/11x_64 OK, now you can stop and start your system and check that you are working on 12c.
Hope this tutorial could help others to accomplish this task.