Aternos 1.21.3 doesn't work

[Adambuild]

❗ Checklist

• I am using the official english version of Slimefun and did not modify the jar.
• I downloaded the official version from the new build site Blob Builds.
• I am using an up to date "DEV" (not "RC") version of Slimefun.
• I am aware that issues related to Slimefun addons need to be reported on their bug trackers and not here.
• I searched for similar open issues and could not find an existing bug report on this.

📍 Description

I have proble with Slimefun plug-in on Aternost on 1.21.3 minecraft java When i start server everything looks like it works byt when i join I didn't find book in inventory and /slimefun doesn't work. I tried it on Spingot/bukkit and Paper/bukkit. Do anyone know why?

📑 Reproduction Steps

1. start server
2. Join server
3. Look in inventory don't find book
4. Try comand /slimefun

💡 Expected Behavior

To find slimefun book or get it from comand.

📷 Screenshots / Videos

No response

📜 Server Log

https://pastebin.com/wwKy6XMN

📂 /error-reports/ folder

No response

💻 Server Software

Other (please specify in your description)

🎮 Minecraft Version

1.20.x

⭐ Slimefun version

Slimefun 4 1156 and 1157

🧭 Other plugins

nothing

[Boomer-1]

slimefun has not released an official version for 1.21. Aternos has mis marked that by mistake. closing this as invalid.