Just to add what the error means is you published the island with persistence scrips and have since either… Removed the scrips and or negatively modified the persistence script.
You can only add values and not remove or negatively modify persistence after you publish for the first time.
This imo is nothing to do with formatting the pc and rather you have either deleted the said script or modified it. All verse and project assets are within your project folder so the fact that you can open the project indicates to me that this is not a issue with UEFN or caused by the pc format rather as i said above you have changed a verse persistence script after the initial publish. To fix simply revert to the original verse script you used for persistence when you initially publish. You can use revision control you import the project again if you need to.