-25251: Code page to set (<code_page_name>) not found in system
table SYSLOADER.CODEPAGE. The privilege to change the content of this table
is restricted to SYSDBA. 
You have executed the command SET CODEPAGE <code_page_name>. The Loader could not find the code page specified in the command in the system table SYSLOADER.CODEPAGE.In order to enter code pages in this system table using the SET CODEPAGE <code_page_name> command, it is necessary to log on to the database as a database system administrator (SYSDBA user) with the Loader.
Log on to the database as a database system administrator using the Loader and re-execute the command.