cannot load pre-update caves world

My caves world that was created prior to the Depths of Duplicity update will not load, giving me the "Dedicated Server Failed To Start" error. Following the steps provided by the "Get More Help" button has failed to fix the issue. My other pre-update caves worlds also have this problem, though the ones that are forest only start fine. There are also no problems with creating a new caves world.

Edit: I have fixed the issue. The problem was that I had allowed dontstarve_dedicated_server_nullrenderer.exe and dontstarve_steam.exe through my firewall, but I had NOT whitelisted the x64 variants of those files through the firewall.