Minecraft FTB no server.jar

OS Name/Version: Debian GNU/Linux 13.6

Product Name/Version: FTB Evolution 1.42.0 (but really any FTB modpack)

Problem Description:

If I try to install an instance of Minecraft Java with a FTB Modpack that doesn´t seem to work. The server starts as vanilla and if switch to FTB and a modpack it just does not download a server.jar for the specified modpack. The mods however are correctly being downloaded.
I tried manually removing the vanilla server.jar but then the modpack download would still not pull the correct one.

I found one post from february last year about this issue where it was said that was due to API changes at FTB. Is that still the case? Newer post about this issue did not get any replies as far as I found them.

Steps to reproduce:

  • Install Minecraft Java Edition instance
  • Remove vanilla minecraft-server.jar
  • Select FTB as source and choose modpack
  • Download modpack
  • Try to start server

Actions taken to resolve so far:
Tried using the store (Beta) instead but this did not change the behaviour.
Tried different FTB modpacks but this did not change the behaviour.

You need to change your Server Type config to the required modloader and version for the modpack you’re trying to run. It’s likely Forge or Neoforge.