I can't save...for some reason.

[[Unknown]]

That message shows when it's trying to write and gets an error about disk space. It doesn't show it willy nilly, so if you see it, there's a problem.

You didn't say what device you're using, so I could assume you're using iOS - which isn't well supported because of Apple restrictions, and often has permission issues preventing save. Or perhaps you're on Android, saving to internal storage with tons of GBs on a removal storage microSD card.

You might even be on a PC, with PPSSPP on a USB stick that's full, but with tons of free space on your hard disk. Or maybe you just ran PPSSPP as administrator the first time, so now when you don't, those administrator-only folders for save data aren't writable.

All of these situations would mean that where PPSSPP is trying to save, it can't. It could be a lot of other things too, like a virus scanner.

So first things first: what device are you using? Where and how is it installed? Does your device have free space on all storage mediums?

-[Unknown]