This is a report for 1.10.2
I have tried to enter the medium on both a server and on single player, both times with the same result. When I try to enter the medium I end up waiting for a very long time while loading terrain (I currently assume indefinitely) and eventually have to just quit. When I try to rejoin into either the single player world or the server, it crashes if on single player, or throws an internal server error on multiplayer. I have not gotten the error from the server admin yet but the error on my minecraft launcher when it crashes is

--- Minecraft Crash Report ----

WARNING: coremods are present:
IvToolkit (IvToolkit-1.3.3-1.10.jar)
AppleCore (AppleCore-mc1.10.2-3.1.1.jar)
ArsMagica2-Preloader (ArsMagica2-1.10.2-1.5.0-18.jar)
Contact their authors BEFORE contacting forge

// Why is it breaking :(

Time: 4/15/18 9:06 PM
Description: Ticking memory connection

java.lang.NullPointerException: Ticking memory connection
at net.minecraftforge.common.BiomeDictionary.containsType(BiomeDictionary.java:440)
at net.minecraftforge.common.BiomeDictionary.isBiomeOfType(BiomeDictionary.java:261)
at ivorius.reccomplex.utils.expression.BiomeExpression$BiomeDictVariableType.lambda$parse$355(BiomeExpression.java:105)
at ivorius.reccomplex.utils.algebra.FunctionExpressionCache.lambda$evaluate$37(FunctionExpressionCache.java:109)
at ivorius.reccomplex.utils.algebra.Algebra$Variable.evaluate(Algebra.java:423)
at ivorius.reccomplex.utils.algebra.FunctionExpressionCache.evaluate(FunctionExpressionCache.java:109)
at ivorius.reccomplex.utils.algebra.FunctionExpressionCache.evaluate(FunctionExpressionCache.java:119)
at ivorius.reccomplex.utils.algebra.BoolFunctionExpressionCache.test(BoolFunctionExpressionCache.java:44)
at ivorius.reccomplex.world.gen.feature.structure.generic.WeightedBiomeMatcher.matches(WeightedBiomeMatcher.java:53)
at ivorius.reccomplex.world.gen.feature.selector.StructureSelector.generationWeightInBiome(StructureSelector.java:79)
at ivorius.reccomplex.world.gen.feature.selector.StructureSelector.generationWeight(StructureSelector.java:60)
at ivorius.reccomplex.world.gen.feature.structure.generic.generation.NaturalGeneration.getGenerationWeight(NaturalGeneration.java:130)
at ivorius.reccomplex.world.gen.feature.selector.StructureSelector.(StructureSelector.java:47)
at ivorius.reccomplex.world.gen.feature.selector.MixingStructureSelector.(MixingStructureSelector.java:29)
at ivorius.reccomplex.world.gen.feature.structure.generic.generation.NaturalGeneration$Cache.lambda$setRegistry$337(NaturalGeneration.java:271)
at ivorius.reccomplex.world.gen.feature.selector.CachedStructureSelectors.get(CachedStructureSelectors.java:39)
at ivorius.reccomplex.world.gen.feature.WorldGenStructures.planStructuresInChunk(WorldGenStructures.java:69)
at ivorius.reccomplex.world.gen.feature.WorldGenStructures.decorate(WorldGenStructures.java:222)
at ivorius.reccomplex.world.gen.feature.GenerationSanityChecker.lambda$init$799(GenerationSanityChecker.java:49)
at net.minecraftforge.fml.common.registry.GameRegistry.generateWorld(GameRegistry.java:120)
at net.minecraft.world.chunk.Chunk.func_186034_a(Chunk.java:1001)
at net.minecraft.world.chunk.Chunk.func_186030_a(Chunk.java:969)
at net.minecraft.world.gen.ChunkProviderServer.func_186025_d(ChunkProviderServer.java:154)
at com.mraof.minestuck.world.WorldProviderLands.func_186061_a(WorldProviderLands.java:215)
at net.minecraft.world.ServerWorldEventHandler.func_72703_a(ServerWorldEventHandler.java:37)
at net.minecraft.world.World.func_72923_a(World.java:1142)
at net.minecraft.world.WorldServer.func_72923_a(WorldServer.java:1118)
at net.minecraft.world.World.func_72838_d(World.java:1133)
at net.minecraft.world.WorldServer.func_72838_d(WorldServer.java:1064)
at net.minecraft.server.management.PlayerList.func_72377_c(PlayerList.java:368)
at net.minecraft.server.management.PlayerList.initializeConnectionToPlayer(PlayerList.java:163)
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.completeServerSideConnection(NetworkDispatcher.java:260)
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.access$100(NetworkDispatcher.java:73)
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher$1.func_73660_a(NetworkDispatcher.java:209)
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:287)
at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:180)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:732)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:613)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:149)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
at java.lang.Thread.run(Thread.java:748)

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

-- Head --
Thread: Server thread
Stacktrace:
at net.minecraftforge.common.BiomeDictionary.containsType(BiomeDictionary.java:440)
at net.minecraftforge.common.BiomeDictionary.isBiomeOfType(BiomeDictionary.java:261)
at ivorius.reccomplex.utils.expression.BiomeExpression$BiomeDictVariableType.lambda$parse$355(BiomeExpression.java:105)
at ivorius.reccomplex.utils.algebra.FunctionExpressionCache.lambda$evaluate$37(FunctionExpressionCache.java:109)
at ivorius.reccomplex.utils.algebra.Algebra$Variable.evaluate(Algebra.java:423)
at ivorius.reccomplex.utils.algebra.FunctionExpressionCache.evaluate(FunctionExpressionCache.java:109)
at ivorius.reccomplex.utils.algebra.FunctionExpressionCache.evaluate(FunctionExpressionCache.java:119)
at ivorius.reccomplex.utils.algebra.BoolFunctionExpressionCache.test(BoolFunctionExpressionCache.java:44)
at ivorius.reccomplex.world.gen.feature.structure.generic.WeightedBiomeMatcher.matches(WeightedBiomeMatcher.java:53)
at ivorius.reccomplex.world.gen.feature.selector.StructureSelector.generationWeightInBiome(StructureSelector.java:79)
at ivorius.reccomplex.world.gen.feature.selector.StructureSelector.generationWeight(StructureSelector.java:60)
at ivorius.reccomplex.world.gen.feature.structure.generic.generation.NaturalGeneration.getGenerationWeight(NaturalGeneration.java:130)
at ivorius.reccomplex.world.gen.feature.selector.StructureSelector.(StructureSelector.java:47)
at ivorius.reccomplex.world.gen.feature.selector.MixingStructureSelector.(MixingStructureSelector.java:29)
at ivorius.reccomplex.world.gen.feature.structure.generic.generation.NaturalGeneration$Cache.lambda$setRegistry$337(NaturalGeneration.java:271)
at ivorius.reccomplex.world.gen.feature.selector.CachedStructureSelectors.get(CachedStructureSelectors.java:39)
at ivorius.reccomplex.world.gen.feature.WorldGenStructures.planStructuresInChunk(WorldGenStructures.java:69)
at ivorius.reccomplex.world.gen.feature.WorldGenStructures.decorate(WorldGenStructures.java:222)
at ivorius.reccomplex.world.gen.feature.GenerationSanityChecker.lambda$init$799(GenerationSanityChecker.java:49)
at net.minecraftforge.fml.common.registry.GameRegistry.generateWorld(GameRegistry.java:120)
at net.minecraft.world.chunk.Chunk.func_186034_a(Chunk.java:1001)
at net.minecraft.world.chunk.Chunk.func_186030_a(Chunk.java:969)
at net.minecraft.world.gen.ChunkProviderServer.func_186025_d(ChunkProviderServer.java:154)
at com.mraof.minestuck.world.WorldProviderLands.func_186061_a(WorldProviderLands.java:215)
at net.minecraft.world.ServerWorldEventHandler.func_72703_a(ServerWorldEventHandler.java:37)
at net.minecraft.world.World.func_72923_a(World.java:1142)
at net.minecraft.world.WorldServer.func_72923_a(WorldServer.java:1118)
at net.minecraft.world.World.func_72838_d(World.java:1133)
at net.minecraft.world.WorldServer.func_72838_d(WorldServer.java:1064)
at net.minecraft.server.management.PlayerList.func_72377_c(PlayerList.java:368)
at net.minecraft.server.management.PlayerList.initializeConnectionToPlayer(PlayerList.java:163)
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.completeServerSideConnection(NetworkDispatcher.java:260)
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher.access$100(NetworkDispatcher.java:73)
at net.minecraftforge.fml.common.network.handshake.NetworkDispatcher$1.func_73660_a(NetworkDispatcher.java:209)
at net.minecraft.network.NetworkManager.func_74428_b(NetworkManager.java:287)

-- Ticking connection --
Details:
Connection: net.minecraft.network.NetworkManager@21e4fc32
Stacktrace:
at net.minecraft.network.NetworkSystem.func_151269_c(NetworkSystem.java:180)
at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:732)
at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:613)
at net.minecraft.server.integrated.IntegratedServer.func_71217_p(IntegratedServer.java:149)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:471)
at java.lang.Thread.run(Thread.java:748)

-- System Details --
Details:
Minecraft Version: 1.10.2
Operating System: Linux (amd64) version 4.13.0-32-generic
Java Version: 1.8.0_131, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 1200947936 bytes (1145 MB) / 2134114304 bytes (2035 MB) up to 2134114304 bytes (2035 MB)
JVM Flags: 6 total; -Xmx2G -Xms2G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 1, tallocated: 12
FML: MCP 9.32 Powered by Forge 12.18.3.2511 24 mods loaded, 24 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored
UCHIJAAAAAA mcp{9.19} [Minecraft Coder Pack] (minecraft.jar)
UCHIJAAAAAA FML{8.0.99.99} [Forge Mod Loader] (forge-1.10.2-12.18.3.2511.jar)
UCHIJAAAAAA Forge{12.18.3.2511} [Minecraft Forge] (forge-1.10.2-12.18.3.2511.jar)
UCHIJAAAAAA ivtoolkit{1.3.3-1.10} [IvToolkit] (minecraft.jar)
UCHIJAAAAAA mercurius_updater{1.0} [mercurius_updater] (MercuriusUpdater-1.10.2.jar)
UCHIJAAAAAA antiqueatlas{4.4.6} [Antique Atlas] (antiqueatlas-1.9.4-4.4.6.jar)
UCHIJAAAAAA antiqueatlasoverlay{1.2} [Antique Atlas Overlay] (antiqueatlas-1.9.4-4.4.6.jar)
UCHIJAAAAAA JEI{3.14.7.420} [Just Enough Items] (jei_1.10.2-3.14.7.420.jar)
UCHIJAAAAAA AppleCore{3.1.1} [AppleCore] (AppleCore-mc1.10.2-3.1.1.jar)
UCHIJAAAAAA arsmagica2{1.5.018} [Ars Magica 2] (ArsMagica2-1.10.2-1.5.0-18.jar)
UCHIJAAAAAA AnimationAPI{1.2.4} [AnimationAPI] (ArsMagica2-1.10.2-1.5.0-18.jar)
UCHIJAAAAAA Baubles{1.3.13} [Baubles] (Baubles-1.10.2-1.3.13.jar)
UCHIJAAAAAA BiomesOPlenty{5.0.0.2236} [Biomes O' Plenty] (BiomesOPlenty-1.10.2-5.0.0.2236-universal.jar)
UCHIJAAAAAA fe{1.3} [Food Expansion] (FoodExpansion1.3.1-1.10.2.jar)
UCHIJAAAAAA mantle{1.10.2-1.1.5.205} [Mantle] (Mantle-1.10.2-1.1.5.jar)
UCHIJAAAAAA minestuck{1.10.2-1.2.207} [Minestuck] (Minestuck-1.10.2-1.2.207.jar)
UCHIJAAAAAA reccomplex{1.4.5-1.10} [Recurrent Complex] (RecurrentComplex-1.4.5-1.10.jar)
UCHIJAAAAAA tconstruct{1.10.2-2.6.5.10} [Tinkers' Construct] (TConstruct-1.10.2-2.6.5.jar)
UCHIJAAAAAA thaumcraft{6.0.BETA8} [Thaumcraft] (Thaumcraft-1.10.2-6.0.BETA8.jar)
UCHIJAAAAAA ThaumicJEI{1.1.2} [ThaumicJEI] (ThaumicJEI-1.10.2-1.1.3-2.jar)
UCHIJAAAAAA bspkrsCore{at_0.9} [bspkrsCore] (Treecapitator-1.10.2-at_0.9.jar)
UCHIJAAAAAA Treecapitator{at_0.9} [Treecapitator] (Treecapitator-1.10.2-at_0.9.jar)
UCHIJAAAAAA icse{1.1.0.0} [I Can See Everything] (Wawla-1.10.2-2.3.2.215.jar)
UCHIJAAAAAA wawla{2.3.2.215} [What Are We Looking At] (Wawla-1.10.2-2.3.2.215.jar)
Loaded coremods (and transformers):
IvToolkit (IvToolkit-1.3.3-1.10.jar)

AppleCore (AppleCore-mc1.10.2-3.1.1.jar)
squeek.applecore.asm.TransformerModuleHandler
ArsMagica2-Preloader (ArsMagica2-1.10.2-1.5.0-18.jar)
am2.asm.Transformer
GL info: ERROR RuntimeException: No OpenGL context found in the current thread.
Pulsar/tconstruct loaded Pulses:
- TinkerCommons (Enabled/Forced)
- TinkerWorld (Enabled/Not Forced)
- TinkerTools (Enabled/Not Forced)
- TinkerHarvestTools (Enabled/Forced)
- TinkerMeleeWeapons (Enabled/Forced)
- TinkerRangedWeapons (Enabled/Forced)
- TinkerModifiers (Enabled/Forced)
- TinkerSmeltery (Enabled/Not Forced)
- TinkerGadgets (Enabled/Not Forced)
- TinkerOredict (Enabled/Forced)
- TinkerIntegration (Enabled/Forced)
- TinkerFluids (Enabled/Forced)
- TinkerMaterials (Enabled/Forced)
- TinkerModelRegister (Enabled/Forced)

Profiler Position: N/A (disabled)
Player Count: 1 / 8; [EntityPlayerMP['HaHa4242'/227, l='New World', x=-308.82, y=4.00, z=-1511.50]]
Type: Integrated Server (map_client.txt)
Is Modded: Definitely; Client brand changed to 'fml,forge'

This is a large problem, not just a medium one. Thanks, and keep up the good work.

Thing is that the1.10 version is basically abandoned at this point
It has simply gone too long since we were on that version, so it's not really going to be updated anymore
So the best course of action would be to simply remove Recurrent Complex since that's the mod that brings up the problem