Unable to load any saves. See the screenshots.
Edit:
I created a new world and a new game and was able to load a save.
I also created a new game on the first world and was unable to load the game - It logged similar messages.
In summary
World A
Save a1 - unable to load (screenshot are from the save)
Save a2 - unable to load.
World B
save b1 - able to load.
[attachment deleted due to age]
That looks like a pretty hefty error log...
I'm thinking that's corrupted rather extensively, Did you mess around with the Dev menu at all?
You're only running core, maybe World A was running mods and you forgot to turn them back on?
I never ever used dev tools or mods. I am 100% vanilla.
Curious, Is the first world from the most recent build? or atleast an Alpha 12 build?
If you're able to make new worlds and create saves from them fine, I'm suspecting it's not a world generation issue.
both are from 0.12.914
I've mulled over it a few days, hoping to find a solution, but I think I'm stumped here.
Looks a lot like the file is corrupted in some way, but I can't see an obvious cause or a fix for that matter.
Sorry. :/ Hope someone else can help.