Recreate your orapw file in $ORACLE_HOME/dbs.
orapwd file=$ORACLE_HOME/dbs/orapw password=sys_password entries=20
Try with complete syntax
perl adbldxml.pl appsuser=apps apppass=apps
I can create as below:
bash-3.2$ perl adbldxml.pl
Starting context file generation for db tier..
Using JVM from /data/ora/testdb/11.2.0/jdk/jre/bin/java to execute java programs..
APPS Password: apps
The log file for this adbldxml session is located at:
Enter the value for Display Variable: 0.0
The context file has been created at: