World crashes with geckolib api

Hello I recently made an animation with blockbench using geckolib api. I used version 3.66 so I can use the older plugin version on blockbench. Then I added it to my mob and added the mob to my mod. Once I load  a world it crashes. The first time I create the world and enter the world the game is frozen for a few seconds then it says saving world and the game crashes. Then if i try loading up the same world, I dont even get in the game, it just crashes. Thank you.