After installed new Morphs I got crashed after login into my server and found that all animals in Mocreautes cause crash for some reason.

There are many error logs report depends on what entity it found first:
Example : Angler

[14:21:29] [Client thread/FATAL]: Reported exception thrown!
[B#534] net.minecraft.util.ReportedException: Ticking entity
[B#534] at net.minecraft.world.World.updateEntities(World.java:1776) ~[amu.class:?]
[B#534] at net.minecraft.client.Minecraft.runTick(Minecraft.java:1847) ~[bib.class:?]
[B#534] at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1098) ~[bib.class:?]
[B#534] at net.minecraft.client.Minecraft.run(Minecraft.java:3942) [bib.class:?]
[B#534] at net.minecraft.client.main.Main.main(SourceFile:123) [Main.class:?]
[B#534] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) ~[?:1.8.0_251]
[B#534] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_251]
[B#534] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source) ~[?:1.8.0_251]
[B#534] at java.lang.reflect.Method.invoke(Unknown Source) ~[?:1.8.0_251]
[B#534] at net.minecraft.launchwrapper.Launch.launch(Launch.java:135) [launchwrapper-1.12.jar:?]
[B#534] at net.minecraft.launchwrapper.Launch.main(Launch.java:28) [launchwrapper-1.12.jar:?]
[B#534] Caused by: java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Boolean
[B#534] at drzhark.mocreatures.entity.MoCEntityTameableAquatic.getIsTamed(MoCEntityTameableAquatic.java:89) ~[MoCEntityTameableAquatic.class:?]
[B#534] at drzhark.mocreatures.entity.MoCEntityTameableAquatic.isEntityInsideOpaqueBlock(MoCEntityTameableAquatic.java:452) ~[MoCEntityTameableAquatic.class:?]
[B#534] at net.minecraft.entity.EntityLivingBase.onEntityUpdate(EntityLivingBase.java:232) ~[vp.class:?]
[B#534] at net.minecraft.entity.EntityLiving.onEntityUpdate(EntityLiving.java:269) ~[vq.class:?]
[B#534] at drzhark.mocreatures.entity.MoCEntityAquatic.onEntityUpdate(MoCEntityAquatic.java:914) ~[MoCEntityAquatic.class:?]
[B#534] at net.minecraft.entity.Entity.onUpdate(Entity.java:389) ~[vg.class:?]
[B#534] at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2096) ~[vp.class:?]
[B#534] at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:377) ~[vq.class:?]
[B#534] at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:1996) ~[amu.class:?]
[B#534] at net.minecraft.world.World.updateEntity(World.java:1958) ~[amu.class:?]
[B#534] at net.minecraft.world.World.redirect$zce000$updateEntity(World.java:5123) ~[amu.class:?]
[B#534] at net.minecraft.world.World.updateEntities(World.java:1762) ~[amu.class:?]
[B#534] ... 10 more
[B#534] [14:21:29] [Client thread/FATAL]: Minecraft ran into a problem! Report saved to: C:\Users\PlusaiCC-Unit-12C\AppData\Roaming.technic\modpacks\wildcalling\crash-reports\crash-2020-05-18_14.21.29-client.txt
[B#534] ---- Minecraft Crash Report ----
[B#534] // You're mean.
[B#534]
[B#534] Time: 2020-05-18 14:21:29 PDT
[B#534] Description: Ticking entity
[B#534]
[B#534] java.lang.ClassCastException: java.lang.Integer cannot be cast to java.lang.Boolean
[B#534] at drzhark.mocreatures.entity.MoCEntityTameableAquatic.getIsTamed(MoCEntityTameableAquatic.java:89)
[B#534] at drzhark.mocreatures.entity.MoCEntityTameableAquatic.isEntityInsideOpaqueBlock(MoCEntityTameableAquatic.java:452)
[B#534] at net.minecraft.entity.EntityLivingBase.onEntityUpdate(EntityLivingBase.java:232)
[B#534] at net.minecraft.entity.EntityLiving.onEntityUpdate(EntityLiving.java:269)
[B#534] at drzhark.mocreatures.entity.MoCEntityAquatic.onEntityUpdate(MoCEntityAquatic.java:914)
[B#534] at net.minecraft.entity.Entity.onUpdate(Entity.java:389)
[B#534] at net.minecraft.entity.EntityLivingBase.onUpdate(EntityLivingBase.java:2096)
[B#534] at net.minecraft.entity.EntityLiving.onUpdate(EntityLiving.java:377)
[B#534] at net.minecraft.world.World.updateEntityWithOptionalForce(World.java:1996)
[B#534] at net.minecraft.world.World.updateEntity(World.java:1958)
[B#534] at net.minecraft.world.World.redirect$zce000$updateEntity(World.java:5123)
[B#534] at net.minecraft.world.World.updateEntities(World.java:1762)
[B#534] at net.minecraft.client.Minecraft.runTick(Minecraft.java:1847)
[B#534] at net.minecraft.client.Minecraft.runGameLoop(Minecraft.java:1098)
[B#534] at net.minecraft.client.Minecraft.run(Minecraft.java:3942)
[B#534] at net.minecraft.client.main.Main.main(SourceFile:123)
[B#534] at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
[B#534] at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
[B#534] at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
[B#534] at java.lang.reflect.Method.invoke(Unknown Source)
[B#534] at net.minecraft.launchwrapper.Launch.launch(Launch.java:135)
[B#534] at net.minecraft.launchwrapper.Launch.main(Launch.java:28)
[B#534]
[B#534]
[B#534] A detailed walkthrough of the error, its code path and all known details is as follows:
[B#534] ---------------------------------------------------------------------------------------
[B#534]
[B#534] -- Entity being ticked --
[B#534] Entity Type: mocreatures:angler (drzhark.mocreatures.entity.aquatic.MoCEntityAngler)
[B#534] Entity ID: 5302
[B#534] Entity Name: Angler
[B#534] Entity's Exact location: 1756.71, 62.00, 3830.85
[B#534] Entity's Block location: World: (1756,62,3830), Chunk: (at 12,3,6 in 109,239; contains blocks 1744,0,3824 to 1759,255,3839), Region: (3,7; contains chunks 96,224 to 127,255, blocks 1536,0,3584 to 2047,255,4095)
[B#534] Entity's Momentum: 0.00, -0.01, 0.00
[B#534] Entity's Passengers: []
[B#534] Entity's Vehicle: ERROR NullPointerException: null
[B#534] Entity NBT: ERROR ReportedException: Saving entity NBT
[B#534]
[B#534] -- Affected level --
[B#534] Level name: MpServer
[B#534] All players: 1 total; [EntityPlayerSP['DeonHNT'/5909, l='MpServer', x=8.50, y=65.00, z=8.50]]
[B#534] Chunk stats: MultiplayerChunkCache: 122, 122
[B#534] Level seed: 0
[B#534] Level generator: ID 06 - BIOMESOP, ver 0. Features enabled: false
[B#534] Level generator options:
[B#534] Level spawn location: World: (8,64,8), Chunk: (at 8,4,8 in 0,0; contains blocks 0,0,0 to 15,255,15), Region: (0,0; contains chunks 0,0 to 31,31, blocks 0,0,0 to 511,255,511)
[B#534] Level time: 22 game time, 22 day time
[B#534] Level dimension: 0
[B#534] Level storage version: 0x00000 - Unknown?
...
Suspected Mods: DrZhark's Mo'Creatures Mod (mocreatures)
[B#534] Launched Version: 1.12.2-forge1.12.2-14.23.5.2847
[B#534] LWJGL: 2.9.4
[B#534] OpenGL: Intel(R) UHD Graphics 620 GL version 4.6.0 - Build 26.20.100.7637, Intel
[B#534] GL Caps: Using GL 1.3 multitexturing.
[B#534] Using GL 1.3 texture combiners.
[B#534] Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
[B#534] Shaders are available because OpenGL 2.1 is supported.
[B#534] VBOs are available because OpenGL 1.5 is supported.
[B#534] Using VBOs: Yes
[B#534] Is Modded: Definitely; Client brand changed to 'fml,forge'
[B#534] Type: Client (map_client.txt)
[B#534] Resource Packs:
[B#534] Current Language: English (US)
[B#534] Profiler Position: N/A (disabled)
[B#534] CPU: 8x Intel(R) Core(TM) i5-8250U CPU @ 1.60GHz
[B#534] Client Crashes Since Restart: 9
[B#534] Integrated Server Crashes Since Restart: 0
[B#534]
[B#534] [14:29:16] [Client thread/ERROR]: ########## GL ERROR ##########
[B#534] [14:29:16] [Client thread/ERROR]: @ VanillaFix GUI Loop
[B#534] [14:29:16] [Client thread/ERROR]: 1280: Invalid enum

As Morph has just been rewritten and released for MC 1.16.5, I am clearing the issue tracker as I have not provided any support Morph for 1.12.2 and earlier. My apologies for not addressing your issue.

I have the same problem, adjust its in update please ichun