When you save,it will load on a PSP,but not an older PPSSPP?

[vsub_]

I'm probably missing something(I wasn't around for a while)
The only game I've seen this for now is Dante Inferno(it's mentioning it not once but twice...probably more on every memory stick access)...what is this about?

I keep older ppsspp version because I used them to clear certain game and I'm not sure if that game will work from start to the end on some newer rev.

[LunaMoo]

Saves were recently fixed in v0.9.8-1572-g0795f79 new versions can read older saves just fine, but once you save the game using this or following builds, it'll not be compatible with versions before the fix was applied.

I'm not sure, but the fix seems to be only applied to encrypted saves(or at least it doesn't seem to have a warning printed for decrypted ones), so if you don't care about psp compatibility, you could try changing in the ppsspp.ini "EncryptSave = True" to False, and possibly decrypted saves from new versions, might still be compatible with older versions. This is just a guess through, so might not work.

[TheDax]

I assume you're referring to this: https://github.com/hrydgard/ppsspp/pull/6515. Basically, all saves will now be saved in a way that is compatible with a real PSP, as they should be. However, this means if try to use these saves on an older build, they'll show up as corrupted data, since they lack the new functionality. If it's going to be a problem, I suggest making a backup of all of your saves so you can have a pristine copy of them for older builds and newer builds.