Do you have the latest version of JOIPlay and the latest RPG Maker plugin for it from here?
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It's patreon but it's a free post. For whatever reason, the patreon links are newer than their actual website. I mention this because I used to get that error with the "Allow External Modules" setting set to on, but now I can't replicate it. So you can first see if "Allow External Modules" is on, and turn it off to see if that fixes it, or you can try the latest download of JOIPlay and the RPG Maker plugin and see if that fixes it. If both don't work you can either fiddle around with the other settings (which is how I have fixed every JOIPlay bug so far), or let me know and I can take a look.
I am hoping to have it finished within 6-8 months, but it certainly could take another year. Shouldn't be two or more though. We are about 80% of the way through the second last dungeon, and the last one will be a lot shorter than the sixth.
