A mod is for a different Minecraft version
Applies to Forge, NeoForge, Fabric, Quilt.
What it looks like in your log
Mod sodium requires minecraft version 1.20.1 or above
What causes it
A mod was built for a different Minecraft version than the one you are running.
How to fix it
Use mods that match your server’s exact Minecraft version.
Not sure this is your problem? Paste your log and Roastd will tell you which of these it actually matched, and what else it found.
Check your own log