[2021] Can´t load older SAVEGAME

Originally posted by ISac: but why they dont fix this ??

Because they could spend time building new code and new stuff, or making sure everything is backward compatible like this was a final released product. Which would you prefer during an Alpha (hint if all the time is spent fixing a few bugs and keeping everything backward compatible that means fewer changes usually and fewer new features). They've said many times eventually that will be a focus but for now major updates mean a restart (or roll-back/opt-in) to an old version but never load saves between different major versions.