Oracle 21c has been released on-premise as you might already know and the base version is 21.3, the first RU released for 21c is in October CPU 2021. [21.4.0.0.211019]

First observation when you download the RU for 21c is the following statement in Oracle portal (there is NO separate OVJM patch anymore…its combined in one patch in DB RU)

I have downloaded the latest Opatch utility 12.2.0.1.27 and copied it under my Oracle home in $ORACLE_HOME/OPatch/ directory

scp -r /opt/Opatch_12.2.0.1.27/OPatch/* $ORACLE_HOME/OPatch/

Shutdown your database and listener

Then go the directory where your patch is downloaded

Then execute the OPatch utility:

$ORACLE_HOME/OPatch/opatch apply

After successfully patching the database binaries, we need to perform post patch activity (datapatch):

sqlplus / as sysdba

SQL> startup

SQL> alter pluggable database all open;

SQL> exit;

cd $ORACLE_HOME/OPatch

./datapatch -verbose

Its highly recommend to run utlrp.sql script against CDB$ROOT and in each pluggable database:

SQL> @?/rdbms/admin/utlrp.sql

To check status of your patch activity:

SQL> select status,action,description from dba_registry_sqlpatch;

Remark: As you know starting from 21c only CDB architecture is supported.

And last step is to patch your JDK binaries, to check your current binaries JDK build number:

// to check current version:

$ORACLE_HOME/jdk/bin/java -version

you can then remove the temporary jdk directory: rm -rf $ORACLE_HOME/jdk.original