lostcities-1.12-2.0.0
forge-1.12.2-14.23.1.2607-installer-win

2 diamond blocks under bed surrounded by skulls and crash report:
crash-2018-02-07_14.36.12-server.txt

This is a new modpack i'm creating, so no Lost Cities config existed before adding this mod, and I changed no settings in the config as I assumed that it would use default settings.

I will check it out. Is this single player or server?

This could be caused by another mod adding an invalid biome. I'll add a test to print out which biome does this.

Singleplayer, and I'm using a new biome generator, so could well be that.

This is a test on build with nothing but the terrain generator mods and Lost Cities - the lack of other mods might make it easier:
crash-2018-02-08_18.36.16-server.txt

One odd thing is that a few times before it crashed it did deliver me to a new world, in a cave and then crashed.

I did a vanilla build with no other mods and tried again - worked fine this time, except that when i made another bed to come back to the Overworld, it created half a bed floating in mid air. I'm wondering if that could be to do with height differences.

Did you modify the lost city configs in any way?

No, haven't touched them yet as I wanted to see the changes in the latest versions before I played with them.

So can you try to remove those too and see if that helps?

Hmm, that last crash you posted seems to indicate there are still other mods present. More specifically:

| UCHIJAAAA | otgcore              | 1.12         | minecraft.jar                        | None                                     |
| UCHIJAAAA | openterraingenerator | v4           | OpenTerrainGenerator-1.12.2 - v4.jar | e9f7847a78c5342af5b0a9e04e5abc0b554d69e0 |
| UCHIJAAAA | biomebundle          | 5.1          | Biome_Bundle-1.12.2-v6.1.jar         | None                                     |

And this is very relevant as those are biome mods

Those are all the mods that make up the world generator - they're all designed to work together. Removing them leaves me at vanilla minecraft with just LostCities added, and that does work, as I've already tested it.

Ok, then the problem is most likely in one of those mods. This evening I will release a new version of Lost Cities that will hopefully show which mod causes the problem

Cool, thanks for that - will be sure to give it a try.

Ok, it would appear that it's probably a bug with OTG not setting up the Biome Registry properly ?

crash-2018-02-09_21.07.07-server.txt

I actually thought that you used your own world gen for the Lost Cities dimension.

Did you want me to contact them about this matter instead ?

I do use my own worldgen but biomes can be from other mods. So yes, you should report this to OTG

It was already reported there under the Biome Bundle issues: BiomeBundle/BiomeBundle#76

Sounds like it's not likely to happen anytime soon. Is there no way to start up a Lost Cities dimension with vanilla worldgen instead ? Which is actually what I want for my build - I don't actually want OTG world gen for the Lost Cities dimension, just the Overworld dimension.

That ticket is about something else. That ticket is about support for OTG world gen with Lost Cities. But this ticket is about a real bug that they are somehow messing up the biome registry. So unrelated

Ah, ok, misunderstood that then.