What's the issue you encountered?

Crash on new worldgen. I had had several lockups, this is the first time I got an actual crash in the logs before it locked up, it never produced a crash report because it locked hard.

How can the issue be reproduced?

Start a server many times while trying to get mods to work clientside and serverside and connect to the server without being rejected without proper error messages from forge.

Logs

debug.log
latest.log

Mod Version

BiomesOPlenty-1.14.3-9.0.0.171-universal

The above seems to suggest it's an issue occurring during structure generation, try removing any mods that add custom structures.