Not sure what's up with that, as I've never had that issue, sorry...I tried full version with the old saved files but there is the same error. I can load and use the old saves but the josy_chat error is there.
I'm wondering if you may have to re-download. In case for some reason your download corrupted.
Usually a corrupted archive will give errors when unpacking though. *shrugs*
Make sure you've download the latest, zip-archive file.. I just downloaded from both anonfile, and uploadheaven, to test..
(dropmefiles link wasn't working for me, files removed) I use 7zip to unpack archives.
To iron out filestructure issues, I suggest unpacking as close to root as possible;
ex: x:\VN\*** <--- final folder before the one with the executable, \game, \lib, and \renpy folders.
Anyways.. on both the versions from anonfile, and uploadhaven, I was able to load up my previous saves.
and skip through episode 6 no props.
What I always do myself every update, is play to the end, then roll back, and manual save just before the summary.
Load that save on next update. And so on.
I always use the full version downloads, and then load up the manual save in next game version..
If you're able to... Start up version 5.1 make a save before the end of episode summary.. (if still got a copy around)
Load that save in 6.1.
See if that helps..
Otherwise, if you select "skip unseen text" in preferences, you can pretty much go through a new playthrough in matter of about half an hour, if wanna test further. (to figure if it's a save, or game issue)
Otherwise I'm out of ideas man.. :/