Faze Allan, I need to know this too. Cause when i played raft on version 1.3 I got really far. Now when version 1.4 is released I can't play on my safed file which I am really proud over. Developer if there is anyway to fix that please go ahead and do that now, I am sure there are plenty of other players that have the same problem as us.
The developer has already said earlier that 1.03 save files are not compatible with 1.04 so there's nothing really to fix here. While they could release a new 1.05 version they would have to build backward compatibility with the old 1.03 and 1.04 files and that's a bunch of work for no payback, other than providing that option to people that need it. A lot to ask for a free game that's only a few months old since development started.