hmm.. #411 closed with no information.
My 1.8 world has crush on starting game with MCA too.
Here is crush report. any idea?

---- Minecraft Crash Report ----
// Everything's going to plan. No, really, that was supposed to happen.

Time: 15/07/16 22:01
Description: Exception ticking world

java.util.ConcurrentModificationException
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
at java.util.HashMap$KeyIterator.next(HashMap.java:1453)
at com.google.common.collect.AbstractMapBasedMultimap$WrappedCollection$WrappedIterator.next(AbstractMapBasedMultimap.java:486)
at net.minecraft.util.ClassInheritanceMultiMap$2.computeNext(SourceFile:90)
at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
at net.minecraft.world.World.func_175650_b(World.java:3119)
at net.minecraft.world.chunk.Chunk.func_76631_c(Chunk.java:952)
at net.minecraftforge.common.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:46)
at net.minecraftforge.common.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:12)
at net.minecraftforge.common.util.AsynchronousExecutor.skipQueue(AsynchronousExecutor.java:344)
at net.minecraftforge.common.util.AsynchronousExecutor.getSkipQueue(AsynchronousExecutor.java:302)
at net.minecraftforge.common.chunkio.ChunkIOExecutor.syncChunkLoad(ChunkIOExecutor.java:12)
at net.minecraft.world.gen.ChunkProviderServer.loadChunk(ChunkProviderServer.java:117)
at net.minecraft.world.gen.ChunkProviderServer.func_73158_c(ChunkProviderServer.java:92)
at net.minecraft.world.gen.ChunkProviderServer.func_73154_d(ChunkProviderServer.java:189)
at net.minecraft.world.World.func_72964_e(World.java:304)
at net.minecraft.world.World.func_175726_f(World.java:299)
at net.minecraft.world.World.func_180495_p(World.java:836)
at net.minecraft.village.Village.func_179860_f(SourceFile:326)
at net.minecraft.village.Village.func_75557_k(SourceFile:312)
at net.minecraft.village.Village.func_75560_a(SourceFile:69)
at net.minecraft.village.VillageCollection.func_75544_a(SourceFile:60)
at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:225)
at WorldServerOF.func_72835_b(WorldServerOF.java:37)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:692)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:598)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:258)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:478)
at java.lang.Thread.run(Thread.java:745)

A detailed walkthrough of the error, its code path and all known details is as follows:

-- Head --
Stacktrace:
at java.util.HashMap$HashIterator.nextNode(HashMap.java:1429)
at java.util.HashMap$KeyIterator.next(HashMap.java:1453)
at com.google.common.collect.AbstractMapBasedMultimap$WrappedCollection$WrappedIterator.next(AbstractMapBasedMultimap.java:486)
at net.minecraft.util.ClassInheritanceMultiMap$2.computeNext(SourceFile:90)
at com.google.common.collect.AbstractIterator.tryToComputeNext(AbstractIterator.java:143)
at com.google.common.collect.AbstractIterator.hasNext(AbstractIterator.java:138)
at net.minecraft.world.World.func_175650_b(World.java:3119)
at net.minecraft.world.chunk.Chunk.func_76631_c(Chunk.java:952)
at net.minecraftforge.common.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:46)
at net.minecraftforge.common.chunkio.ChunkIOProvider.callStage2(ChunkIOProvider.java:12)
at net.minecraftforge.common.util.AsynchronousExecutor.skipQueue(AsynchronousExecutor.java:344)
at net.minecraftforge.common.util.AsynchronousExecutor.getSkipQueue(AsynchronousExecutor.java:302)
at net.minecraftforge.common.chunkio.ChunkIOExecutor.syncChunkLoad(ChunkIOExecutor.java:12)
at net.minecraft.world.gen.ChunkProviderServer.loadChunk(ChunkProviderServer.java:117)
at net.minecraft.world.gen.ChunkProviderServer.func_73158_c(ChunkProviderServer.java:92)
at net.minecraft.world.gen.ChunkProviderServer.func_73154_d(ChunkProviderServer.java:189)
at net.minecraft.world.World.func_72964_e(World.java:304)
at net.minecraft.world.World.func_175726_f(World.java:299)
at net.minecraft.world.World.func_180495_p(World.java:836)
at net.minecraft.village.Village.func_179860_f(SourceFile:326)
at net.minecraft.village.Village.func_75557_k(SourceFile:312)
at net.minecraft.village.Village.func_75560_a(SourceFile:69)
at net.minecraft.village.VillageCollection.func_75544_a(SourceFile:60)
at net.minecraft.world.WorldServer.func_72835_b(WorldServer.java:225)
at WorldServerOF.func_72835_b(WorldServerOF.java:37)

-- Affected level --
Details:
Level name: New World001
All players: 0 total; []
Chunk stats: ServerChunkCache: 626 Drop: 0
Level seed: -8918104364449433835
Level generator: ID 00 - default, ver 1. Features enabled: true
Level generator options:
Level spawn location: -18.00,64.00,262.00 - World: (-18,64,262), Chunk: (at 14,4,6 in -2,16; contains blocks -32,0,256 to -17,255,271), Region: (-1,0; contains chunks -32,0 to -1,31, blocks -512,0,0 to -1,255,511)
Level time: 10389156 game time, 12325403 day time
Level dimension: 0
Level storage version: 0x04ABD - Anvil
Level weather: Rain time: 88179 (now: false), thunder time: 76776 (now: false)
Level game mode: Game mode: survival (ID 0). Hardcore: false. Cheats: false
Stacktrace:
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:692)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:598)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:258)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:478)
at java.lang.Thread.run(Thread.java:745)

-- System Details --
Details:
Minecraft Version: 1.8
Operating System: Windows 7 (amd64) version 6.1
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 289869048 bytes (276 MB) / 758927360 bytes (723 MB) up to 1060372480 bytes (1011 MB)
Mod Pack: 1.8-SNAPSHOT-r365-b46-2015-01-25_23-01-16
LiteLoader Mods: 1 loaded mod(s)
- MAtmos-UnofficialBeta version r29 for 1.8
LaunchWrapper: 22 active transformer(s)
- Transformer: net.minecraftforge.fml.common.asm.transformers.PatchingTransformer
- Transformer: optifine.OptiFineClassTransformer
- Transformer: $wrapper.net.minecraftforge.fml.common.asm.transformers.BlamingTransformer
- Transformer: $wrapper.net.minecraftforge.fml.common.asm.transformers.MarkerTransformer
- Transformer: $wrapper.net.minecraftforge.fml.common.asm.transformers.SideTransformer
- Transformer: $wrapper.net.minecraftforge.fml.common.asm.transformers.EventSubscriptionTransformer
- Transformer: com.mumfrey.liteloader.transformers.event.EventProxyTransformer
- Transformer: com.mumfrey.liteloader.launch.LiteLoaderTransformer
- Transformer: com.mumfrey.liteloader.client.transformers.CrashReportTransformer
- Transformer: shadersmod.transform.SMCClassTransformer
- Transformer: net.minecraftforge.fml.common.asm.transformers.DeobfuscationTransformer
- Transformer: net.minecraftforge.fml.common.asm.transformers.AccessTransformer
- Transformer: net.minecraftforge.transformers.ForgeAccessTransformer
- Transformer: net.minecraftforge.fml.common.asm.transformers.ModAccessTransformer
- Transformer: net.minecraftforge.fml.common.asm.transformers.ItemStackTransformer
- Transformer: net.minecraftforge.fml.common.asm.transformers.TerminalTransformer
- Transformer: com.mumfrey.liteloader.transformers.event.EventTransformer
- Transformer: com.mumfrey.liteloader.common.transformers.LiteLoaderPacketTransformer
- Transformer: com.mumfrey.liteloader.client.transformers.LiteLoaderEventInjectionTransformer
- Transformer: com.mumfrey.liteloader.client.transformers.MinecraftTransformer
- Transformer: com.mumfrey.liteloader.transformers.event.json.ModEventInjectionTransformer
- Transformer: net.minecraftforge.fml.common.asm.transformers.ModAPITransformer
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 12, tallocated: 94
FML: MCP v9.10 FML v8.0.37.1334 Minecraft Forge 11.14.1.1334 Optifine OptiFine_1.8_HD_U_D1 5 mods loaded, 5 mods active
mcp{9.05} Minecraft Coder Pack Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
FML{8.0.37.1334} Forge Mod Loader Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
Forge{11.14.1.1334} Minecraft Forge Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
RadixCore{2.0.3-1.8} RadixCore Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
MCA{5.0.6.1-1.8} Minecraft Comes Alive Unloaded->Constructed->Pre-initialized->Initialized->Post-initialized->Available->Available->Available->Available
Loaded coremods (and transformers):
Profiler Position: N/A (disabled)
Player Count: 0 / 8; []
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'fml,forge'

It was closed as the user did not provide enough information. Marking this for review.

Should be fixed in 8d7ab24