I think it doesn't work cause we are using Alien Biomes, without it it just works perfect, could you try to fix this issue?

Crash Log:
Error while running event modmashsplinterunderground::on_chunk_generated (ID 12)
Unknown tile name: underground-dark-dirt-1
stack traceback:
[C]: in function 'set_tiles'
...splinterunderground__/prototypes/scripts/underground.lua:525: in function 'generate_surface_area'
...splinterunderground__/prototypes/scripts/underground.lua:622: in function <...splinterunderground__/prototypes/scripts/underground.lua:596>
[C]: in function 'force_generate_chunk_requests'
...splinterunderground__/prototypes/scripts/underground.lua:421: in function 'generate_surface_area'
...splinterunderground__/prototypes/scripts/underground.lua:2184: in function 'local_ensure_can_place_entity_inner'
...splinterunderground__/prototypes/scripts/underground.lua:2242: in function 'local_ensure_can_place_entity'
...splinterunderground__/prototypes/scripts/underground.lua:2286: in function 'local_underground_added_std'
...splinterunderground__/prototypes/scripts/underground.lua:2574: in function 'local_underground_added'
...splinterunderground__/prototypes/scripts/underground.lua:3199: in function <...splinterunderground__/prototypes/scripts/underground.lua:3198>
stack traceback:
[C]: in function 'force_generate_chunk_requests'
...splinterunderground__/prototypes/scripts/underground.lua:421: in function 'generate_surface_area'
...splinterunderground__/prototypes/scripts/underground.lua:2184: in function 'local_ensure_can_place_entity_inner'
...splinterunderground__/prototypes/scripts/underground.lua:2242: in function 'local_ensure_can_place_entity'
...splinterunderground__/prototypes/scripts/underground.lua:2286: in function 'local_underground_added_std'
...splinterunderground__/prototypes/scripts/underground.lua:2574: in function 'local_underground_added'
...splinterunderground__/prototypes/scripts/underground.lua:3199: in function <...splinterunderground__/prototypes/scripts/underground.lua:3198>

Sounds like alien biomes has removed required tiles create my by mod. Not sure why it would bother doing that as that sort of thing buggers other mods too if they are using their own tiles. Will see what I can do.

Okay, thank you very much!

It's not alien biomes. Just tested works fine
What other mods?

unless a setting is changed

Sorry it's not that either I cannot replicate, I'm going to try move the tile creation to final fixes and if dirt not found try use landfill tile as base.
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Okay thats wierd...
I am going to sleep now, so i will test it later, and then i can give you a List of all mods I currently use.

okay, so I updated the ModMash mods, restarted the game and then I had the Error: "Reached id limit for tile . After getting back in the game I removed the mod Dectorio, and now it works fine...

Placing Underground Shaft now works fine :D

ok so Dectorio is possibly exceeding hard limit so not a lot I can do about that

okay but thanks for your time