java.sql.SQLException: Non supported character set (add orai18n.jar in your classpath) - Oracle Enterprise Manager 13.5 upgrade/install

The repository of EM Cloud Control was historically situated in the database of different from AL32UTF8 characterset. The upgrade procedure of EM is stucking into the error in the title. Had the character set of repository database been AL32UTF8, this error would have never been happen (but I found this is a tricky way because encrypted EM key is kept in the repository and it depends on the id (guid ?) of database as well).

The following steps was made to resolve.

1. Unzip em13500_linux64.bin into temporary catalog

% unzip -q /u02/install/13.5/em13500_linux64.bin -d /u02/install/13.5/unzip/

2. Unzip EM installer, put the file orai18n.jar from existing 19c oracle home and make some modifications :

% cd /u02/install/13.5/unzip/Disk1/stage/Components/oracle.sysman.em.installer/13.5.0.0.0/DataFiles

% mkdir unzip_fg1

% unzip -q filegroup1.jar -d unzip_fg1

% cd unzip_fg1/oui/em

% cp $ORACLE_HOME/jlib/orai18n.jar .

% cp -p ../../../compDef.xml ../../../compDef.xml.orig

% vi ../../../compDef.xml 

Put the line describing orai18n.jar into compDef.xml

...

             <file size="1661488" dest="orai18n.jar"/>
...

% cd ../.. ; pwd

/u02/install/13.5/unzip/Disk1/stage/Components/oracle.sysman.em.installer/13.5.0.0.0/DataFiles/unzip_fg1

% cp -p ../filegroup1.jar ../filegroup1.jar.orig

% zip -r ../filegroup1.jar *

% cd /u02/install/13.5/unzip/Disk1/install

% cp -p oraparam.ini oraparam.ini.orig

% cp -p linux64/oraparam.ini linux64/oraparam.ini.orig

Modify oraparam.ini to include the new jar file in the classpath :

...

EXT_CLASSPATH=oui/em/orai18n.jar,...

...

% cd /u02/install/13.5

% cp -p em13500_linux64.bin em13500_linux64.bin.orig

% cd unzip

% zip -u ../em13500_linux64.bin Disk1/stage/Components/oracle.sysman.em.installer/13.5.0.0.0/compDef.xml

% zip -u ../em13500_linux64.bin Disk1/stage/Components/oracle.sysman.em.installer/13.5.0.0.0/DataFiles/filegroup1.jar

% zip -u ../em13500_linux64.bin Disk1/install/oraparam.ini

% zip -u ../em13500_linux64.bin Disk1/install/linux64/oraparam.ini

3. That's it ! Run the installation or upgrade 😀