one of the new features in 12c is having the passwords in the password file being by default case sensitive. also, you can configure password file for the new system account users (SYSDG—-> for data guard, SYSBACKUP —-> for backup operations and administration)

Example of password file command:

orapwd file=EMO_DB_PASS entries=10 sysbackup=y sysdg=y

*** the  EMO_DB file (password file) will be created in the directory where you are currently in.

as shown in the above picture passwords are required to be entered for SYS,SYSBACKUP,SYSDG accounts.

the following command will be executed to access the database as SYSDG user for verification:

sqlplus SYSDG/cocoChannel7 as SYSDG