So, I'm trying to set up a Custom modpack server, It has a few Tech mods, Pixelmon, and Mystcraft, but Mystcraft has been unstable only recently, and I want to know why, and how to fix it. up until the 16th world was generated, It was working fine, but now the server crashes every single time a world is created, Idk why this is happening, it doesn't happen on my other servers, so I have no clue,
You've created too many dimensions and you are overloading the game. The more worlds you create, the more unstable your game will become. I tend to try not to create more than 5 worlds at a time, if that.
If you really want to create more worlds, go into the saves folder, into the folder for your world, and delete some of the old dimensions that you aren't using any more.