I have updated the mods and now I get the following message when starting the game:
Error while running setup for space-location prototype "velora" (planet): big-rock (entity) does not have an autoplace specification.

When I reverted the mod to the version 1.2.0 I had no issues.

Does the issue occur when launching the game or when loading a save file? If it happens at launch, there’s nothing in the mod update mechanism that would cause such an error. You’re likely experiencing a conflict with one of your other mods. If it happens when loading a save file, please provide the save file causing the issue—I haven’t been able to reproduce it on my end.

At launching the game.

Is there a way that I can see what mod interferes withoud deaktivating a bunch in the hope to find the correct one?

Until versio 1.3.0 it has no issues, with version 1.3.1+ the message appears.

Unfortunately, the only way to pinpoint the conflict is by disabling mods. I would start by disabling all planet mods and then re-enabling them one by one. The fact that the game crashes on version 1.3.1+ is to be expected. Planet generation was significantly changed in version 1.3.1.

with Velora 1.43 and alien-biomes 0.7.4 i am getting this error

Error loading mods: Error while running setup for space-location prototype "velora" (planet): big-rock (entity) does not have an autoplace specification.

Mods to deaktivate:

Velora (1.43)
redrawn-space-compat-fixes (1.0.42)
Better-Planets (1.1.9)
PlanetsLib (1.17.1)
YAIM904-d00b-core (0.0.3)
configuarble-nukes (0.9.10)

After Remove Alien-Biomes i am getting this error because of Mulana 2.1.79

Error loading mods: Cycle in technology tree detected.

production-sience-pack
-> bob-heat-shiled
-> rocket-silo
-> space-platform
-> space-platform-thruster
-> thruster-oxidizer
-> thruster-fuel
-> planet-discovery-mulana
-> mulana-anorthite-processing
-> mulana-aluminia-processing
-> mulana-aluminium-processing
-> mulana-alice-propellant
-> space-sience-pack
-> production-sience-pack

After I also removed the Mulana Mod, the game launches with Velora 1.43.
With alien-biomes_0.4.7 and planet-mulana_2.1.79, I have to downgrade to velora_1.3.0.
This is just the result of my mod pack, consisting of over 470 mods. I hope it proves helpful.

Wow, thanks. That's really helpful. I think the problem is either with Mulana or alien-biomes. I'll check it out soon and let you know.

I've fixed the incompatibility with alien-biomes, and I haven't encountered any issues with Mulana (if I understand correctly, this is the Muluna mod: https://mods.factorio.com/mod/planet-muluna). Apparently, there is some other mod conflict in your build, the final stage of which is a looping tech tree and a notification from my mod. Currently, all three mods run together normally on their latest versions and do not cause any issues.

Thanks for the quick fix. Now everything is running perfectly again. Your change also fixes the problem with Mulana. I don't know where that came from, but with over 470 mods, something like that can happen. I like to try out a lot of mods but I can now play on your current version thanks to you. Thanks again.

That has also fixed it for me, thanks a lot.