I have a world I generated in 1.7 with TerrainControl, a world generation plugin. The world is pre-generated with worldborder, so I don't need to be concerned about new generation. I no longer use the plugin and haven't used it in 1.8 - 1.12.2. I've not had any issues in versions prior to 1.13. Now if I try to upgrade the world to 1.13 - 1.15, some chunks when a player loads them, crash the server. I've done --forceUpdate when going from 1.12.2 -> 1.13 then again each subsequent major update. Log (no plugins installed): https://privatebin.net/?a1bee31e307bb5d9#H9tsjpFiTjyYpnzpuwPaeqF51wR1uhC9RH4pZkWVyPwU Now I know the chunks aren't corrupted, because if I generate a new world, using TerrainControl in 1.12.2 with the exact same seed, the same chunks as my production server will crash the local newly generated server in spigot 1.13.2. I suspect, this is to do with custom generated ocean biomes. The plugin would make "seaweed" using bamboo and vines under the ocean. In 1.13, the aquatic update that probably causes major issues. Although, I have noticed not all the crashes have been in ocean biomes (I would upload the logs, but they were in paper not spigot). Is there anything I can do to get this world working past 1.12?