Although you can still use the catupgrd.sql script, it is deprecated starting with Oracle Database 12c and will be removed in future releases.
Oracle recommends database upgrades be performed with the new Parallel Upgrade Utility, catctl.pl.
If you choose to run the catupgrd.sql script instead of running catctl.pl, doing so now requires an additional input parameter as follows:
SQL> @catupgrd.sql PARALLEL=NO
If you run catupgrd.sql without the parameter, then Oracle displays the following error message:
The catupgrd.sql script is being deprecated in the 12.1 release of Oracle Database. Customers are encouraged to use catctl.pl as the replacement for catupgrd.sql when upgrading the database dictionary.
$ORACLE_HOME/perl/bin/perl catctl.pl -n 4 catupgrd.sql
Refer to the Oracle Database Upgrade Guide for more information.