For some reason it can't load.

I have no idea what file I should upload. 🤷🏻‍♂️

Post your latest.log. You can find it in %APPDATA%\.minecraft\.latest.log

latest.log

*edit: i found this---

[Render thread/FATAL] [mixin/]: Mixin apply failed mowziesmobs.mixins.json:GeoModelMixin -> software.bernie.geckolib.model.GeoModel: org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException @at("STORE" ordinal=0 index=-1) on software/bernie/geckolib/model/GeoModel::currentTimeInjected with priority 1000 cannot inject into software/bernie/geckolib/model/GeoModel::handleAnimations(Lsoftware/bernie/geckolib/core/animatable/GeoAnimatable;JLsoftware/bernie/geckolib/core/animation/AnimationState;)V merged by elocindev.geckoanimfix.mixin.common.GeoModelMixin with priority 1000 [PREINJECT Applicator Phase -> mowziesmobs.mixins.json:GeoModelMixin -> Prepare Injections -> -> localvar$bjg000$currentTimeInjected(DLsoftware/bernie/geckolib/core/animatable/GeoAnimatable;JLsoftware/bernie/geckolib/core/animation/AnimationState;)D -> Prepare]
org.spongepowered.asm.mixin.injection.throwables.InvalidInjectionException: @at("STORE" ordinal=0 index=-1) on software/bernie/geckolib/model/GeoModel::currentTimeInjected with priority 1000 cannot inject into software/bernie/geckolib/model/GeoModel::handleAnimations(Lsoftware/bernie/geckolib/core/animatable/GeoAnimatable;JLsoftware/bernie/geckolib/core/animation/AnimationState;)V merged by elocindev.geckoanimfix.mixin.common.GeoModelMixin with priority 1000 [PREINJECT Applicator Phase -> mowziesmobs.mixins.json:GeoModelMixin -> Prepare Injections -> -> localvar$bjg000$currentTimeInjected(DLsoftware/bernie/geckolib/core/animatable/GeoAnimatable;JLsoftware/bernie/geckolib/core/animation/AnimationState;)D -> Prepare]

Oh, is that the Geckolib/Iris compat mod? Yeah you'll have to remove it.

What is elocindev.geckoanimfix?

Wow that's true, now it works!!! TY