In Furstenstein when you use the switch to open the spiders nest, when you try to leave the hall the switch is in, it says "Failed to load: Arachne Furstenstein"
That means you're missing a file. Possibly due to skipping an update while using the "update files" or something broke during the download.
You can fix this by downloading the full game version again, and copying the entire content of the www/save folder of the old game folder to the same location in the new game folder. Make sure to copy everything from the save folder, or you won't see your saves.
Hi Ryen I redownloaded the full game version again (I enjoy replaying the entire game so I delete the previous game on my computer and add the new one) - of the latest update (23.12.16) - and I am still getting the failed to load for Arachne. When the Furstenstein update first came out via the full game it worked just fine on my computer (MacOS) so I do not know why the problem is occurring now.