Solutions not working, packaging error createprocess() returned 2

I just finished my first prototype/gaming demo and I am trying to package it. I was able to successfully do it for the beta of the demo. Two different versions, actually. I was able to get them working for playtesting, but this last one that I want to actually upload publicly is not working.

It’s the "couldn’t start createprocess() returned 2 " packaging/delivery error.

I double checked that “For distribution” was turned on and also “include prerequisites installer”.

It did however work when I ran it locally, zipped and unzipped, but not when I downloaded and tried it on the same computer.

But as soon as it was delivered by web or flashdrive I got the error.

I’m just wanting to upload it to Itch.io, so if it’ll work for that purpose I guess it’s fine, but I’d prefer it not having any errors.

I want to check with you all before I migrate everything into a new UE file and package it from there.