[18:50:40] [main/ERROR] [prefab]: The mod prefab appears to have an invalid event annotation EventHandler. This annotation can only apply to methods with recognized event arguments - it will not be called
[18:50:40] [main/ERROR] [prefab]: The mod prefab appears to have an invalid event annotation EventHandler. This annotation can only apply to methods with recognized event arguments - it will not be called

Debug Crash - Forced it so you can see mods present etc.
https://gist.github.com/P3rf3ctXZer0/46725302808738ce3c759914ea215761

This was fixed when 1.3.0.12 was released yesterday.

Thank you!

Thanks! I will take a look at this tomorrow.

Found out what the problem is. Forge changed the "MissingMapping" event in 1.12 from an EventHandler like Pre-Initialization/Initialization to regular SubscribeEvent types like OnPlayerDeath/OnDrops/Etc.

This issue shouldn't cause any problems unless you are upgrading from a 1.10.2 world directly to 1.12.X since in 1.11 is when I changed the names of the blocks/items.

Glad I could help; going that extra mile at preventing crashes!