about saves - you may need the original account. on the ps3 (at least), the account id is present for any account that's signed into psn. I found the same id in the id.dat on my vita, since I'm using the same account there. the same id is likely on my ps4. if you've never signed in to psn with an account/profile, the account id will be blank. you can see 15 characters of the 16 character account id in a ps3 save. the full account id (likely an added 0 at the beginning) is present in the id.dat (use a text editor to open). saves are much easier to manage with no account id. I do plan to restore my ps vita on 3.60 to remove the account, since you can only have on account, and I really don't want to use account switcher which I read still forces a format. the account id is everywhere in system (vita) in multiple partitions.
I'm not sure if psn content will work either without an act.dat which means signing in to psn to activate the system, so I may have to hold off on restoring my ps4 system until we can access psn again. I only have a few saves on my system, none of which are very far since I only play the wii u anymore, so restoring either the ps4 or the vita (have only one save here) should be relatively painless. my concern is the games.
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oh, I think a ps3 save will show 16 characters for the account id if your first character (the one at the far left) isn't a 0. my guess is that the ps4 uses an idps (online id) and a psid (offline id). the idps is the id sent to sony; the psid is included in saves and such. the ps3 and the vita have both.