java.util.ConcurrentModificationException
at java.util.ArrayList$Itr.checkForComodification(Unknown Source)
at java.util.ArrayList$Itr.next(Unknown Source)
at hardcorequesting.io.SaveHandler.saveAllQuestSets(SaveHandler.java:124)
at hardcorequesting.quests.QuestSet.saveAll(QuestSet.java:83)
at hardcorequesting.quests.QuestLine.saveAll(QuestLine.java:129)
at hardcorequesting.event.WorldEventListener.onSave(WorldEventListener.java:29)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_579_WorldEventListener_onSave_Save.invoke(.dynamic)
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90)
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:185)
at net.minecraft.world.WorldServer.func_73044_a(WorldServer.java:1014)
at net.minecraft.server.MinecraftServer.func_71267_a(MinecraftServer.java:355)
at net.minecraft.server.integrated.IntegratedServer.func_71267_a(IntegratedServer.java:216)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:134)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
at java.lang.Thread.run(Unknown Source)

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

-- System Details --
Details:
Minecraft Version: 1.10.2
Operating System: Windows 10 (amd64) version 10.0
Java Version: 1.8.0_91, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 2329142520 bytes (2221 MB) / 3224371200 bytes (3075 MB) up to 3224371200 bytes (3075 MB)
JVM Flags: 3 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xms1664m -Xmx3200m
IntCache: cache: 0, tcache: 0, allocated: 13, tallocated: 95
FML: MCP 9.32 Powered by Forge 12.18.3.2316 106 mods loaded, 106 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
UCHIJAAAA mcp{9.19} [Minecraft Coder Pack] (minecraft.jar)
UCHIJAAAA FML{8.0.99.99} [Forge Mod Loader] (forge-1.10.2-12.18.3.2316-universal.jar)
UCHIJAAAA Forge{12.18.3.2316} [Minecraft Forge] (forge-1.10.2-12.18.3.2316-universal.jar)
UCHIJAAAA ivtoolkit{1.3.3-1.10} [IvToolkit] (minecraft.jar)
UCHIJAAAA backpacks16840{3.1.5} [Backpacks!] (zz-backpacks 1.10.2 - 3.1.5.jar)
UCHIJAAAA foamfixcore{7.7.4} [FoamFixCore] (minecraft.jar)
UCHIJAAAA fenceoverhaul{1.2.1} [Fence Overhaul] ([1.10.x]FenceOverhaul-1.2.1.jar)
UCHIJAAAA architecturecraft{1.7.3} [ArchitectureCraft] (ArchitectureCraft-1.7.3-mc1.10.2.jar)
UCHIJAAAA Quark{r1.1-70} [Quark] (Quark-r1.1-70 (1).jar)
UCHIJAAAA AutoRegLib{1.0-2} [AutoRegLib] (AutoRegLib-1.0-2 (2).jar)
UCHIJAAAA Baubles{1.3.11} [Baubles] (Baubles-1.10.2-1.3.11.jar)
UCHIJAAAA BetterAchievements{0.3.3.10} [Better Achievements] (BetterAchievements-1.10.2-0.3.3.10.jar)
UCHIJAAAA betterbuilderswands{0.9.3} [Better Builder's Wands] (BetterBuildersWands-1.10.2-0.9.3.187+c619800.jar)
UCHIJAAAA BetterHorseHud{1.0} [Better Horse Hud] (BetterHorseHud-[1.9-1.10.2]-1.0.jar)
UCHIJAAAA betterthanmending{@Version@} [Better Than Mending] (BetterThanMending-0.10.0.jar)
UCHIJAAAA JEI{3.14.7.420} [Just Enough Items] (jei_1.10.2-3.14.7.420.jar)
UCHIJAAAA blockdrops{1.1.0} [Block Drops] (BlockDrops-1.10.2-1.1.0.jar)
UCHIJAAAA bloodmoon{1.5.1} [Bloodmoon] (Bloodmoon-MC1.10.2-1.5.1.jar)
UCHIJAAAA bonemealablebabies{1.0.0a} [Bone Meal-able Babies] (bonemealablebabies-1.0.0a.jar)
UCHIJAAAA bookshelf{1.4.4.347} [Bookshelf] (Bookshelf-1.10.2-1.4.4.347.jar)
UCHIJAAAA carpentersblocks{3.4.001 POC} [Carpenter's Blocks] (Carpenter's Blocks v3.4.001 POC - MC 1.10.2.jar)
UCHIJAAAA Chameleon{1.10-2.2.2} [Chameleon] (Chameleon-1.10-2.2.2.jar)
UCHIJAAAA mcmultipart{1.3.0_87} [MCMultiPart] (MCMultiPart-experimental-2.0.0_88-universal.jar)
UCHIJAAAA chiselsandbits{12.9} [Chisels & Bits] (chiselsandbits-12.9.jar)
UCHIJAAAA CB{1.0.0} [Congrats Button] (congrats_button-1.10.2-1.0.0.jar)
UCHIJAAAA controlling{1.0.4} [Controlling] (Controlling-1.0.4.jar)
UCHIJAAAA XaeroCraftWP{1.3.1} [Craftable Waypoints] (Craftable_Waypoints_1.3.1_Forge_1.10.2 (1).jar)
UCHIJAAAA craftingtweaks{6.1.16} [Crafting Tweaks] (CraftingTweaks_1.10.2-6.1.16.jar)
UCHIJAAAA MineTweaker3{3.0.16} [MineTweaker 3] (CraftTweaker-1.10.2-3.0.16.jar)
UCHIJAAAA ctgui{1.0.0} [CT-GUI] (CraftTweaker-1.10.2-3.0.16.jar)
UCHIJAAAA cropdusting{0.6} [CropDusting] (CropDusting-0.6-[1.9.4-1.10-1.10.2].jar)
UCHIJAAAA CustomBackgrounds{1.0} [Custom Backgrounds] (CustomBackgrounds-MC1.9.4-1.1 (1).jar)
UCHIJAAAA cyberware{beta-0.2.10} [Cyberware] (cyberware-1.9.4-1.10.2-beta-0.2.10.jar)
UCHIJAAAA Waila{1.7.0} [Waila] (Waila-1.7.0-B3_1.9.4.jar)
UCHIJAAAA darkutils{1.1.7.111} [Dark Utilities] (DarkUtilities-1.10.2-1.1.7.111.jar)
UCHIJAAAA ding{1.0.1} [Ding] (Ding-1.10.2-1.0.1.jar)
UCHIJAAAA dungeontactics{DT-0.12.5} [DungeonTactics] (DungeonTactics-1.10.2-0.12.5.jar)
UCHIJAAAA elevatorid{1.3.0} [Elevator Mod] (ElevatorMod[V.1.3.0][MC.1.10.2].jar)
UCHIJAAAA csb_ench_table{1.1} [Lapis Stays in the Enchanting Table] (EnchantingTable-1.10-1.1.jar)
UCHIJAAAA immersiveengineering{0.10-61} [Immersive Engineering] (ImmersiveEngineering-0.10-61.jar)
UCHIJAAAA Mekanism{9.2.1} [Mekanism] (Mekanism-1.10.2-9.2.1.298.jar)
UCHIJAAAA exnihiloomnia{1.2.4} [Ex Nihilo Omnia] (exnihiloomnia-1.2.4.jar)
UCHIJAAAA excompressum{2.0.97} [Ex Compressum] (ExCompressum_1.10.2-2.0.97.jar)
UCHIJAAAA ExtraBitManipulation{1.10.2-2.2.1} [Extra Bit Manipulation] (ExtraBitManipulation-1.10.2-2.2.1.jar)
UCHIJAAAA FastLeaveDecay{1.2.3} [Fast Leave Decay] (FastLeaveDecay-MC1.10.2-1.2.3.jar)
UCHIJAAAA foamfix{@Version@} [FoamFix] (foamfix-0.7.0-beta2-anarchy.jar)
UCHIJAAAA forgelin{1.4.1} [Forgelin] (Forgelin-1.4.1.jar)
UCHIJAAAA guideapi{@Version@} [Guide-API] (Guide-API-1.10.2-2.0.2-45.jar)
UCHIJAAAA helpfixer{1.0} [HelpFixer] (HelpFixer-1.10.2-1.4.15 (1).jar)
UCHIJAAAA HardcoreQuesting{1.10.2-5.0.0beta4} [Hardcore Questing Mode] (HQM-New Heights-1.10.2-5.0.0beta4 (1).jar)
UCHIJAAAA immersivepetroleum{1.0.6} [Immersive Petroleum] (immersivepetroleum-1.10.2-1.0.6.jar)
UCHIJAAAA inventorytweaks{1.61-58-a1fd884} [Inventory Tweaks] (InventoryTweaks-1.61-58.jar)
UCHIJAAAA jeresources{0.5.8.98} [Just Enough Resources] (JustEnoughResources-1.10.2-0.5.8.98.jar)
UCHIJAAAA KeepingInventory{2.1} [Keeping Inventory] (KeepingInventory-1.10.2-2.1.jar)
UCHIJAAAA shadowmc{3.6.1} [ShadowMC] (ShadowMC-1.10.2-3.6.1.jar)
UCHIJAAAA largeveins{@Version@} [Large Veins] (LargeVeins-1.10.2-1.0.0.jar)
UCHIJAAAA llibrary{1.7.6} [LLibrary] (llibrary-1.7.6-1.10.2.jar)
UCHIJAAAA literalascension{1.10.2-1.0.2.2} [Literal Ascension] (literalascension-1.10.2-1.0.2.2.jar)
UCHIJAAAA login_shield{1.10.2-19-gd16e7e0} [Login Shield] (Login_Shield-1.10.2-19-gd16e7e0.jar)
UCHIJAAAA malisiscore{1.10.2-4.2.9} [MalisisCore] (malisiscore-1.10.2-4.2.9.jar)
UCHIJAAAA malisisblocks{1.10.2-4.1.3} [Malisis Blocks] (malisisblocks-1.10.2-4.1.3.jar)
UCHIJAAAA malisisdoors{1.10.2-5.1.6} [MalisisDoors] (malisisdoors-1.10.2-5.1.6.jar)
UCHIJAAAA MekanismGenerators{9.2.1} [MekanismGenerators] (MekanismGenerators-1.10.2-9.2.1.295.jar)
UCHIJAAAA MekanismTools{9.2.1} [MekanismTools] (MekanismTools-1.10.2-9.2.1.295.jar)
UCHIJAAAA MekkitThings{1.0.1} [MekkitThings] (MekkitMod.jar)
UCHIJAAAA miab{1.5.0.1} [Meme in a bottle] (MemeInABottle-1.5.0.1.jar)
UCHIJAAAA mtrm{1.2.1.20} [MineTweakerRecipeMaker] (MineTweakerRecipeMaker-1.10.2-1.2.1.20.jar)
UCHIJAAAA missing_pieces{4.1.1} [Missing Pieces] (missing_pieces-1.10.2-4.1.1.jar)
UCHIJAAAA testdummy{1.11} [MmmMmmMmmMmm] (MmmMmmMmmMmm-1.11.jar)
UCHIJAAAA ModNameTooltip{1.6.0} [Mod Name Tooltip] (modnametooltip_1.10.2-1.6.0.jar)
UCHIJAAAA mousetweaks{2.8} [Mouse Tweaks] (MouseTweaks-2.8-mc1.10.2.jar)
UCHIJAAAA mowziesmobs{1.3.2} [Mowzie's Mobs] (mowziesmobs-1.3.2.jar)
UCHIJAAAA naturescompass{1.3.0} [Nature's Compass] (NaturesCompass-1.10.2-1.3.0.jar)
UCHIJAAAA NoFov{1.0.1} [No Fov] (NoFov-MC1.9.4-1.0.1.jar)
UCHIJAAAA openglider{@Version@} [Open Glider] (OpenGlider-1.10.2-1.0.0.jar)
UCHIJAAAA pillar_extension_quark{2.1.0} [Corail Pillar - Quark Extension] (pillar_extension_quark-2.1.0.jar)
UCHIJAAAA ping{1.2.2} [Ping] (Ping-1.10.X-1.2.2.B7-universal (1).jar)
UCHIJAAAA pumpkisplode{1.10.2-r2} [PumpkiSplode] (PumpkiSplode-1.10.2-r2.jar)
UCHIJAAAA randomthings{3.7.7.1} [Random Things] (RandomThings-MC1.10.2-3.7.7.1.jar)
UCHIJAAAA reccomplex{1.4.4-1.10} [Recurrent Complex] (RecurrentComplex-1.4.4-1.10.jar)
UCHIJAAAA redstoneremote{@Version@} [Redstone Remote] (RedstoneRemote-1.10.2-1.0.0.jar)
UCHIJAAAA refinedstorage{1.2.26} [Refined Storage] (refinedstorage-1.2.26.jar)
UCHIJAAAA rftools{5.62} [RFTools] (rftools-1.10-5.62.jar)
UCHIJAAAA rftoolscontrol{1.5.2} [RFTools Control] (rftoolsctrl-1.10-1.5.2.jar)
UCHIJAAAA signpic{2.6.1} [SignPicture] (SignPicture-1.10.2-2.6.1-universal.jar)
UCHIJAAAA simplemagnet{1.10.2-1.2.2} [Simple Magnet] (simplemagnet-1.10.2-1.2.2.jar)
UCHIJAAAA snad{1.10.2-1.6.09.20a} [Snad] (Snad-1.10.2-1.6.09.20a (1).jar)
UCHIJAAAA stg{1.0.2} [SwingThroughGrass] (stg-1.0.2.jar)
UCHIJAAAA strait{1.10-0.3} [Strait] (strait-1.10-0.3.jar)
UCHIJAAAA terrariamod{1.3} [Terraria Mod] (TerrariaMod-1.2.jar)
UCHIJAAAA testmodpleaseignore{0.0.4-gamma} [Test Mod Please Ignore] (testmodpleaseignore-0.0.4-gamma.jar)
UCHIJAAAA thejungle{1.0.194} [Welcome to the Jungle] (The Jungle-1.015.1102.jar)
UCHIJAAAA thutcore{3.11.1} [ThutCore] (thutcore-3.11.1.jar)
UCHIJAAAA thuttech{@Version@} [Thut's Tech] (thuttech-4.0.10.b.jar)
UCHIJAAAA tickdynamic{1.0.0} [Tick Dynamic] (TickDynamic-1.10.2-1.0.0.jar)
UCHIJAAAA trustcircle{1.10.2-r4} [TrustCircle] (TrustCircle-1.10.2-r4.jar)
UCHIJAAAA ts2k16{1.0.3} [Twerk-Sim 2K16] (TS2K16-1.0.3.jar)
UCHIJAAAA underphangables{1.0.2} [Underp Hangables] (underphangables-1.10.2-1.0.2 (1).jar)
UCHIJAAAA va{1.10.2-1.6.1} [Vanilla Automation] (va-1.10.2-1.6.1.jar)
UCHIJAAAA WailaHarvestability{1.1.9} [Waila Harvestability] (WailaHarvestability-mc1.10.2-1.1.9.jar)
UCHIJAAAA wanionlib{1.10.2-1.3} [WanionLib] (WanionLib-1.10.2-1.3.jar)
UCHIJAAAA weaponcaseloot{4.0.3} [WeaponCaseLoot] (weaponcaseloot-1.10.2-4.0.3.jar)
UCHIJAAAA witherskelefix{1.7.0} [Wither Skeleton Tweaks] (Wither Skeleton Tweaks-1.10.2-1.7.2.jar)
UCHIJAAAA wopper{1.10.2-r1} [Wopper] (Wopper-1.10.2-r1.jar)
UCHIJAAAA corail_pillar{2.0.0} [Corail Pillar] (corail_pillar-2.0.0-1.10.2.jar)
UCHIJAAAA UniDict{1.10.2-2.4} [UniDict] (UniDict-1.10.2-2.4.jar)
Loaded coremods (and transformers):
BookshelfLoadingPlugin (Bookshelf-1.10.2-1.4.4.347.jar)
net.darkhax.bookshelf.asm.BookshelfTransformerManager
LoadingHook (Mekanism-1.10.2-9.2.1.298.jar)

MalisisCorePlugin (malisiscore-1.10.2-4.2.9.jar)
net.malisis.core.util.chunkcollision.ChunkCollisionTransformer
net.malisis.core.util.chunkblock.ChunkBlockTransformer
net.malisis.core.renderer.transformer.MalisisRendererTransformer
net.malisis.core.renderer.icon.asm.TextureMapTransformer
net.malisis.core.util.clientnotif.ClientNotifTransformer
LoadingPlugin (RandomThings-MC1.10.2-3.7.7.1.jar)
lumien.randomthings.asm.ClassTransformer
LoadingPlugin (TickDynamic-1.10.2-1.0.0.jar)
com.wildex999.patcher.TransformerPatcher
com.wildex999.patcher.EntityInjector
LoadingPlugin (Quark-r1.1-70 (1).jar)
vazkii.quark.base.asm.ClassTransformer
literalascension (literalascension-1.10.2-1.0.2.2.jar)
com.jamieswhiteshirt.literalascension.core.patcher.LiteralAscensionRuntimePatcher
SignPictureCorePlugin (SignPicture-1.10.2-2.6.1-universal.jar)
com.kamesuta.mc.signpic.asm.SignPictureTransformer
Do not report to Forge! Remove FoamFixAPI (or replace with FoamFixAPI-Lawful) and try again. (foamfix-0.7.0-beta2-anarchy.jar)
pl.asie.foamfix.coremod.FoamFixTransformer
LoadingPlugin (Bloodmoon-MC1.10.2-1.5.1.jar)
lumien.bloodmoon.asm.ClassTransformer
FMLPlugin (InventoryTweaks-1.61-58.jar)
invtweaks.forge.asm.ContainerTransformer
IvToolkit (IvToolkit-1.3.3-1.10.jar)

ForgelinPlugin (Forgelin-1.4.1.jar)

llibrary (llibrary-1.7.6-1.10.2.jar)
net.ilexiconn.llibrary.server.core.plugin.LLibraryTransformer
net.ilexiconn.llibrary.server.core.patcher.LLibraryRuntimePatcher
BCModPlugin (zz-backpacks 1.10.2 - 3.1.5.jar)
brad16840.common.asm.ClassTransformer
GL info: ERROR RuntimeException: No OpenGL context found in the current thread.
Profiler Position: N/A (disabled)
Player Count: 1 / 8; [EntityPlayerMP[''/438, l='B2 still unfixed configs', x=294.22, y=73.23, z=2110.49]]
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'fml,forge'
[00:24:04] [Client thread/INFO] [STDOUT]: [net.minecraft.init.Bootstrap:func_179870_a:560]: #@!@# Game crashed! Crash report saved to: #@!@# C:\Users\Arlo\Desktop\Mincerafts\MultiMC\instances\Mekkit\minecraft\crash-reports\crash-2017-07-23_00.24.03-server.txt
[00:24:04] [Client thread/INFO] [FML]: Waiting for the server to terminate/save.
[00:24:04] [Server thread/INFO] [FML]: Unloading dimension 0
[00:24:04] [Server thread/INFO] [FML]: Unloading dimension -42
[00:24:04] [Server thread/INFO] [FML]: Unloading dimension -343800852
[00:24:04] [Server thread/INFO] [FML]: Applying holder lookups
[00:24:04] [Server thread/INFO] [FML]: Holder lookups applied
[00:24:04] [Server thread/INFO] [mcjty.lib.varia.Logging]: RFTools: server is stopping. Shutting down gracefully
[00:24:04] [Server thread/INFO] [FML]: The state engine was in incorrect state SERVER_STOPPING and forced into state SERVER_STOPPED. Errors may have been discarded.
[00:24:04] [Client thread/INFO] [FML]: Server terminated.
[00:24:05] [Client Shutdown Thread/INFO]: Stopping server
[00:24:05] [Client Shutdown Thread/INFO]: Saving players
[00:24:05] [Client Shutdown Thread/INFO]: lost connection: TextComponent{text='Server closed', siblings=[], style=Style{hasParent=false, color=null, bold=null, italic=null, underlined=null, obfuscated=null, clickEvent=null, hoverEvent=null, insertion=null}}
[00:24:05] [Client Shutdown Thread/INFO]: left the game
AL lib: (EE) alc_cleanup: 1 device not closed
Process exited with code -1.

Fixed for 1.12. Backport only if I have a stable 1.12.2/1.13 version of HQM