A mod is missing a dependency
Applies to Forge, NeoForge, Fabric, Quilt.
What causes it
One of your mods needs another mod that is not installed.
How to fix it
The log names the missing mod: add it, or remove the mod that requires it.
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