For some reason, all of the world pre-generation mods I tried to use end up crashing at some point.
https://pastebin.com/6h9K2hS4 - the last error I have received when I tried to use Chunky to pre-generate the world.
Forge version: 40.1.59
The Lost Cities version: 5.3.1
Chunky version: 1.2.164

I have no clue how chunky works but maybe it's doing something with worldgen that it isn't supposed to do. Anyway can you give me more details about how you are generating the world? What profile? Any custom assets?

I tried other world pre-generation mods as well, such as Chunk-Pregenerator and World Pre Generator, and even datapack for world pre-generation, but all of them end up crashing at some point with about the same error.

I'm using rarecities profile, no custom assets or anything.

And it works if you just start your world normally without pregen?

I just released Loste Cities 5.3.2. This version will NOT fix your problem. However it should give more information about what's going wrong and may help me figure out the issue. Would be nice if you could try this and send me the full log + crash report. Thanks!

Tried to use Chunk-Pregenerator v4.0.4 again, got this error.
And here's debug.log.

Edit: another debug.log, but with Chunky mod.
Edit №2: crash-report.log, this time I've been using datapack for world pre-generation I've been linking above.

You didn't answer my previous question though. Does Lost Cities work if you just run it normally without pregen?

I've removed the datapack, launched the server and tried to join the game. Got the exact same error as in above mentioned crash-report.log after loading the chunks around the place where it's crashed previously.

I have absolutely no idea what the problem is. I just tried it on a server I made for this purpose and it works perfectly

Can you give me more details how you created your server? What exactly are you doing? How did you configure it? How did you configure Lost Cities? What other mods do you have?

Then how is it possible that three completely different world pre-generation mods and a datapack are crashing the server with the same net.minecraft.ReportedException: Feature placement error Caused by: java.lang.RuntimeException: Error getting building type 'null'!??

I have installed Forge server, dropped Lost Cities and one of the world pre-generation mods into mods folder, started the server, initiated world pre-generation, got an error after some time at some point, that won't let me continue world generation.
I have already been saying what I did in Lost Cities configuration files.
No mods other than Lost Cities and pre-generation mods.

No I mean. How did you setup the server to actually use Lost Cities worldgen? Because by default it doesn't do that. You need to edit a config to enable Lost Cities as explained on the CurseForge page. I'd like to see how you did that

Also no need to be angry with me. I'm also trying to figure out what's wrong. I can't reproduce the problem so I'd like to know what it is that we're doing differently

All I did is changed selectedProfile parameter to rarecities in lostcities-server.toml. That's it.

Weird. Well at the moment I have no more clues. Also just got confirmation from other people who managed to get the latest version of Lost Cities to run fine on a server. So really no idea what's wrong

Try to pre-generate the world using Chunky mod by setting a world border at 0, 0 with a 10000 block radius and generate chunks inside.

It's at 3.47%. At what point does it crash for you?

It's running. So far no problems. I'll let it run for a while

This is going slow. It's currently at 1.55%

I have to stop this. I can't let my computer on for 10 more hours. I stopped it at 5.5%. No crashes