Oracle Password File Version
You can migrate the password file with the input_file option of orapwd.

Example:

[oracle@o71 ~]$ orapwd file=test format=12

Enter password for SYS:
[oracle@o71 ~]$ orapwd describe file=test
Password file Description : format=12
[oracle@o71 ~]$ orapwd file=test2 input_file=test format=12.2
[oracle@o71 ~]$ orapwd describe file=test2
Password file Description : format=12.2