But I don't feel comfortable changing group and permissions unless I know I won't mess something other up.
Corruption with user password history file occurs due to various reasons and causes users and administrators NOT to allow a change to user passwords.
Description The /etc/security/and /etc/security/files are database files created and maintained by Database Manager (DBM) subroutines. The password list contains multiple pairs of a lastupdate value and an encrypted, null-terminated password.
The files maintain a list of previous user passwords. This password list is a key's associated content and the lastupdate value is a 4-byte, unsigned long.
Find out by exploring the file /etc/passwd and see if you can find the name there and how it is written exactly (maybe you have made a typing error while creating the user?