DB Upgrade to 19c | preupgrade_fixups.sql fails with error

 Issue : 

SQL> @/u02/app/oracle/cfgtoollogs/XXXX/preupgrade/2021-07-07205429/naerppch_stby/preupgrade_fixups.sql

DECLARE

*

ERROR at line 1:

ORA-29284: file read error

ORA-06512: at "SYS.UTL_FILE", line 106

ORA-06512: at "SYS.UTL_FILE", line 746

ORA-06512: at "SYS.DBMS_PREUP", line 3352

ORA-06512: at "SYS.DBMS_PREUP", line 10503

ORA-06512: at line 13

Fix :

$echo $ORA_NLS10 

$  unset ORA_NLS10 and run the script again.

$ echo $ORA_NLS10