Authentication Token Manipulation Error

While changing password for user on server error appeared as Authentication Token Manipulation Error.
Example:

#passwd user
Authentication Token Manipulation Error

This error is being shown as /etc/shadowed (password files) doesn’t have entry for this user.

.i.e. /etc/passwd has entry for this user, but /etc/shadow doesn’t.

FIX:

You can either add the entry manually in file /etc/shadow or You can use command pwconv to recreate missing entry under shadow file.