Merge branch 'mc1.15/feedback2' into mc1.15/dev

# Conflicts:
#	src/generated/resources/.cache/cache
#	src/generated/resources/assets/create/lang/unfinished/de_de.json
#	src/generated/resources/assets/create/lang/unfinished/fr_fr.json
#	src/generated/resources/assets/create/lang/unfinished/it_it.json
#	src/generated/resources/assets/create/lang/unfinished/ja_jp.json
#	src/generated/resources/assets/create/lang/unfinished/ko_kr.json
#	src/generated/resources/assets/create/lang/unfinished/nl_nl.json
#	src/generated/resources/assets/create/lang/unfinished/pt_br.json
#	src/generated/resources/assets/create/lang/unfinished/ru_ru.json
#	src/generated/resources/assets/create/lang/unfinished/zh_cn.json
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/Contraption.java
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/BearingContraption.java
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/ClockworkContraption.java
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/StabilizedContraption.java
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/MountedContraption.java
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/PistonContraption.java
#	src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/pulley/PulleyContraption.java

src/generated/resources/assets/create/lang/en_us.json

@@ -822,6 +822,12 @@
 	"create.gui.goggles.kinetic_stats": "Kinetic Stats:",
 	"create.gui.goggles.at_current_speed": "at current speed",
 	"create.gui.goggles.pole_length": "Pole Length:",
+	"create.gui.assembly.exception": "This Contraption was unable to assemble:",
+	"create.gui.assembly.exception.unmovableBlock": "Unmovable Block (%4$s) at [%1$s %2$s %3$s]",
+	"create.gui.assembly.exception.chunkNotLoaded": "The Block at [%1$s %2$s %3$s] was not in a loaded chunk",
+	"create.gui.assembly.exception.structureTooLarge": "There are too many Blocks included in the contraption.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.tooManyPistonPoles": "There are too many extension Poles attached to this Piston.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.noPistonPoles": "The Piston is missing some extension Poles",
 	"create.gui.gauge.info_header": "Gauge Information:",
 	"create.gui.speedometer.title": "Rotation Speed",
 	"create.gui.stressometer.title": "Network Stress",

src/generated/resources/assets/create/lang/unfinished/de_de.json

@@ -823,6 +823,12 @@
 	"create.gui.goggles.kinetic_stats": "UNLOCALIZED: Kinetic Stats:",
 	"create.gui.goggles.at_current_speed": "UNLOCALIZED: at current speed",
 	"create.gui.goggles.pole_length": "UNLOCALIZED: Pole Length:",
+	"create.gui.assembly.exception": "UNLOCALIZED: This Contraption was unable to assemble:",
+	"create.gui.assembly.exception.unmovableBlock": "UNLOCALIZED: Unmovable Block (%4$s) at [%1$s %2$s %3$s]",
+	"create.gui.assembly.exception.chunkNotLoaded": "UNLOCALIZED: The Block at [%1$s %2$s %3$s] was not in a loaded chunk",
+	"create.gui.assembly.exception.structureTooLarge": "UNLOCALIZED: There are too many Blocks included in the contraption.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.tooManyPistonPoles": "UNLOCALIZED: There are too many extension Poles attached to this Piston.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.noPistonPoles": "UNLOCALIZED: The Piston is missing some extension Poles",
 	"create.gui.gauge.info_header": "UNLOCALIZED: Gauge Information:",
 	"create.gui.speedometer.title": "UNLOCALIZED: Rotation Speed",
 	"create.gui.stressometer.title": "UNLOCALIZED: Network Stress",

src/main/java/com/simibubi/create/content/contraptions/base/GeneratingKineticTileEntity.java

@@ -38,7 +38,7 @@ public abstract class GeneratingKineticTileEntity extends KineticTileEntity {
 		if (!(tileEntity instanceof KineticTileEntity))
 			return;
 		KineticTileEntity sourceTe = (KineticTileEntity) tileEntity;
-		if (reActivateSource && sourceTe != null && Math.abs(sourceTe.getSpeed()) >= Math.abs(getGeneratedSpeed()))
+		if (reActivateSource && Math.abs(sourceTe.getSpeed()) >= Math.abs(getGeneratedSpeed()))
 			reActivateSource = false;
 	}
 

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/AssemblyException.java

@@ -0,0 +1,52 @@
+package com.simibubi.create.content.contraptions.components.structureMovement;
+
+import com.simibubi.create.foundation.config.AllConfigs;
+import net.minecraft.block.BlockState;
+import net.minecraft.util.math.BlockPos;
+import net.minecraft.util.text.ITextComponent;
+import net.minecraft.util.text.TranslationTextComponent;
+
+public class AssemblyException extends Exception {
+	public final ITextComponent component;
+
+	public AssemblyException(ITextComponent component) {
+		this.component = component;
+	}
+
+	public AssemblyException(String langKey, Object... objects) {
+		this(new TranslationTextComponent("create.gui.assembly.exception." + langKey, objects));
+	}
+
+	public static AssemblyException unmovableBlock(BlockPos pos, BlockState state) {
+		return new AssemblyException("unmovableBlock",
+				pos.getX(),
+				pos.getY(),
+				pos.getZ(),
+				new TranslationTextComponent(state.getBlock().getTranslationKey()));
+	}
+
+	public static AssemblyException unloadedChunk(BlockPos pos) {
+		return new AssemblyException("chunkNotLoaded",
+				pos.getX(),
+				pos.getY(),
+				pos.getZ());
+	}
+
+	public static AssemblyException structureTooLarge() {
+		return new AssemblyException("structureTooLarge",
+				AllConfigs.SERVER.kinetics.maxBlocksMoved.get());
+	}
+
+	public static AssemblyException tooManyPistonPoles() {
+		return new AssemblyException("tooManyPistonPoles",
+				AllConfigs.SERVER.kinetics.maxPistonPoles.get());
+	}
+
+	public static AssemblyException noPistonPoles() {
+		return new AssemblyException("noPistonPoles");
+	}
+
+	public String getFormattedText() {
+		return component.getFormattedText();
+	}
+}

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/BlockMovementTraits.java

@@ -53,8 +53,7 @@ import net.minecraft.world.World;
 
 public class BlockMovementTraits {
 
-	public static boolean movementNecessary(World world, BlockPos pos) {
+	public static boolean movementNecessary(BlockState state, World world, BlockPos pos) {
-		BlockState state = world.getBlockState(pos);
 		if (isBrittle(state))
 			return true;
 		if (state.getBlock() instanceof FenceGateBlock)
@@ -68,18 +67,17 @@ public class BlockMovementTraits {
 		return true;
 	}
 
-	public static boolean movementAllowed(World world, BlockPos pos) {
+	public static boolean movementAllowed(BlockState state, World world, BlockPos pos) {
-		BlockState blockState = world.getBlockState(pos);
+		Block block = state.getBlock();
-		Block block = blockState.getBlock();
 		if (block instanceof AbstractChassisBlock)
 			return true;
-		if (blockState.getBlockHardness(world, pos) == -1)
+		if (state.getBlockHardness(world, pos) == -1)
 			return false;
-		if (AllBlockTags.NON_MOVABLE.matches(blockState))
+		if (AllBlockTags.NON_MOVABLE.matches(state))
 			return false;
 
 		// Move controllers only when they aren't moving
-		if (block instanceof MechanicalPistonBlock && blockState.get(MechanicalPistonBlock.STATE) != PistonState.MOVING)
+		if (block instanceof MechanicalPistonBlock && state.get(MechanicalPistonBlock.STATE) != PistonState.MOVING)
 			return true;
 		if (block instanceof MechanicalBearingBlock) {
 			TileEntity te = world.getTileEntity(pos);
@@ -97,11 +95,11 @@ public class BlockMovementTraits {
 				return !((PulleyTileEntity) te).running;
 		}
 
-		if (AllBlocks.BELT.has(blockState))
+		if (AllBlocks.BELT.has(state))
 			return true;
-		if (blockState.getBlock() instanceof GrindstoneBlock)
+		if (state.getBlock() instanceof GrindstoneBlock)
 			return true;
-		return blockState.getPushReaction() != PushReaction.BLOCK;
+		return state.getPushReaction() != PushReaction.BLOCK;
 	}
 
 	/**

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/Contraption.java

@@ -1,26 +1,5 @@
 package com.simibubi.create.content.contraptions.components.structureMovement;
 
-import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isExtensionPole;
-import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isPistonHead;
-
-import java.util.ArrayList;
-import java.util.Arrays;
-import java.util.HashMap;
-import java.util.HashSet;
-import java.util.Iterator;
-import java.util.List;
-import java.util.Map;
-import java.util.Optional;
-import java.util.Set;
-import java.util.UUID;
-import java.util.function.BiConsumer;
-import java.util.stream.Collectors;
-
-import javax.annotation.Nullable;
-
-import org.apache.commons.lang3.tuple.MutablePair;
-import org.apache.commons.lang3.tuple.Pair;
-
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllMovementBehaviours;
 import com.simibubi.create.content.contraptions.base.IRotate;
@@ -55,15 +34,7 @@ import com.simibubi.create.foundation.utility.NBTHelper;
 import com.simibubi.create.foundation.utility.NBTProcessors;
 import com.simibubi.create.foundation.utility.VecHelper;
 import com.simibubi.create.foundation.utility.worldWrappers.WrappedWorld;
-
+import net.minecraft.block.*;
-import net.minecraft.block.AbstractButtonBlock;
-import net.minecraft.block.Block;
-import net.minecraft.block.BlockState;
-import net.minecraft.block.Blocks;
-import net.minecraft.block.ChestBlock;
-import net.minecraft.block.DoorBlock;
-import net.minecraft.block.IWaterLoggable;
-import net.minecraft.block.PressurePlateBlock;
 import net.minecraft.block.material.PushReaction;
 import net.minecraft.entity.Entity;
 import net.minecraft.fluid.Fluids;
@@ -96,6 +67,16 @@ import net.minecraftforge.fluids.capability.IFluidHandler.FluidAction;
 import net.minecraftforge.fluids.capability.templates.FluidTank;
 import net.minecraftforge.items.IItemHandlerModifiable;
 import net.minecraftforge.items.wrapper.CombinedInvWrapper;
+import org.apache.commons.lang3.tuple.MutablePair;
+import org.apache.commons.lang3.tuple.Pair;
+
+import javax.annotation.Nullable;
+import java.util.*;
+import java.util.function.BiConsumer;
+import java.util.stream.Collectors;
+
+import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isExtensionPole;
+import static com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.isPistonHead;
 
 public abstract class Contraption {
 
@@ -139,7 +120,7 @@ public abstract class Contraption {
 		stabilizedSubContraptions = new HashMap<>();
 	}
 
-	public abstract boolean assemble(World world, BlockPos pos);
+	public abstract boolean assemble(World world, BlockPos pos) throws AssemblyException;
 
 	public abstract boolean canBeStabilized(Direction facing, BlockPos localPos);
 
@@ -154,7 +135,7 @@ public abstract class Contraption {
 	}
 
 	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction forcedDirection,
-		List<BlockPos> frontier) {
+		Queue<BlockPos> frontier) throws AssemblyException {
 		return true;
 	}
 
@@ -165,9 +146,9 @@ public abstract class Contraption {
 		return contraption;
 	}
 
-	public boolean searchMovedStructure(World world, BlockPos pos, @Nullable Direction forcedDirection) {
+	public boolean searchMovedStructure(World world, BlockPos pos, @Nullable Direction forcedDirection) throws AssemblyException {
 		initialPassengers.clear();
-		List<BlockPos> frontier = new ArrayList<>();
+		Queue<BlockPos> frontier = new LinkedList<>();
 		Set<BlockPos> visited = new HashSet<>();
 		anchor = pos;
 
@@ -181,10 +162,10 @@ public abstract class Contraption {
 		for (int limit = 100000; limit > 0; limit--) {
 			if (frontier.isEmpty())
 				return true;
-			if (!moveBlock(world, frontier.remove(0), forcedDirection, frontier, visited))
+			if (!moveBlock(world, forcedDirection, frontier, visited))
 				return false;
 		}
-		return false;
+		throw AssemblyException.structureTooLarge();
 	}
 
 	public void onEntityCreated(AbstractContraptionEntity entity) {
@@ -196,8 +177,12 @@ public abstract class Contraption {
 			StabilizedContraption subContraption = new StabilizedContraption(face);
 			World world = entity.world;
 			BlockPos pos = blockFace.getPos();
-			if (!subContraption.assemble(world, pos))
+			try {
+				if (!subContraption.assemble(world, pos))
+					continue;
+			} catch (AssemblyException e) {
 				continue;
+			}
 			subContraption.removeBlocksFromWorld(world, BlockPos.ZERO);
 			OrientedContraptionEntity movedContraption =
 				OrientedContraptionEntity.create(world, subContraption, Optional.of(face));
@@ -247,20 +232,25 @@ public abstract class Contraption {
 		fluidStorage.forEach((pos, mfs) -> mfs.tick(entity, pos, world.isRemote));
 	}
 
-	protected boolean moveBlock(World world, BlockPos pos, @Nullable Direction forcedDirection, List<BlockPos> frontier,
+	/** move the first block in frontier queue */
-		Set<BlockPos> visited) {
+	protected boolean moveBlock(World world, @Nullable Direction forcedDirection, Queue<BlockPos> frontier,
-		visited.add(pos);
+		Set<BlockPos> visited) throws AssemblyException {
-		frontier.remove(pos);
+		BlockPos pos = frontier.poll();
-
+		if (pos == null)
-		if (!world.isBlockPresent(pos))
 			return false;
+		visited.add(pos);
+
+		if (World.isOutsideBuildHeight(pos))
+			return true;
+		if (!world.isBlockPresent(pos))
+			throw AssemblyException.unloadedChunk(pos);
 		if (isAnchoringBlockAt(pos))
 			return true;
-		if (!BlockMovementTraits.movementNecessary(world, pos))
-			return true;
-		if (!movementAllowed(world, pos))
-			return false;
 		BlockState state = world.getBlockState(pos);
+		if (!BlockMovementTraits.movementNecessary(state, world, pos))
+			return true;
+		if (!movementAllowed(state, world, pos))
+			throw AssemblyException.unmovableBlock(pos, state);
 		if (state.getBlock() instanceof AbstractChassisBlock
 			&& !moveChassis(world, pos, forcedDirection, frontier, visited))
 			return false;
@@ -306,9 +296,10 @@ public abstract class Contraption {
 		}
 
 		// Cart assemblers attach themselves
-		BlockState stateBelow = world.getBlockState(pos.down());
+		BlockPos posDown = pos.down();
-		if (!visited.contains(pos.down()) && AllBlocks.CART_ASSEMBLER.has(stateBelow))
+		BlockState stateBelow = world.getBlockState(posDown);
-			frontier.add(pos.down());
+		if (!visited.contains(posDown) && AllBlocks.CART_ASSEMBLER.has(stateBelow))
+			frontier.add(posDown);
 
 		Map<Direction, SuperGlueEntity> superglue = SuperGlueHandler.gatherGlue(world, pos);
 
@@ -318,9 +309,9 @@ public abstract class Contraption {
 			BlockState blockState = world.getBlockState(offsetPos);
 			if (isAnchoringBlockAt(offsetPos))
 				continue;
-			if (!movementAllowed(world, offsetPos)) {
+			if (!movementAllowed(blockState, world, offsetPos)) {
 				if (offset == forcedDirection)
-					return false;
+					throw AssemblyException.unmovableBlock(pos, state);
 				continue;
 			}
 
@@ -349,10 +340,13 @@ public abstract class Contraption {
 		}
 
 		addBlock(pos, capture(world, pos));
-		return blocks.size() <= AllConfigs.SERVER.kinetics.maxBlocksMoved.get();
+		if (blocks.size() <= AllConfigs.SERVER.kinetics.maxBlocksMoved.get())
+			return true;
+		else
+			throw AssemblyException.structureTooLarge();
 	}
 
-	protected void movePistonHead(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void movePistonHead(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		Direction direction = state.get(MechanicalPistonHeadBlock.FACING);
 		BlockPos offset = pos.offset(direction.getOpposite());
@@ -374,7 +368,7 @@ public abstract class Contraption {
 		}
 	}
 
-	protected void movePistonPole(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void movePistonPole(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		for (Direction d : Iterate.directionsInAxis(state.get(PistonExtensionPoleBlock.FACING)
 			.getAxis())) {
@@ -397,7 +391,7 @@ public abstract class Contraption {
 		}
 	}
 
-	protected void moveGantryPinion(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void moveGantryPinion(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		BlockPos offset = pos.offset(state.get(GantryPinionBlock.FACING));
 		if (!visited.contains(offset))
@@ -413,7 +407,7 @@ public abstract class Contraption {
 		}
 	}
 
-	protected void moveGantryShaft(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	protected void moveGantryShaft(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited,
 		BlockState state) {
 		for (Direction d : Iterate.directions) {
 			BlockPos offset = pos.offset(d);
@@ -429,7 +423,7 @@ public abstract class Contraption {
 		}
 	}
 
-	private void moveBearing(BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
+	private void moveBearing(BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
 		Direction facing = state.get(MechanicalBearingBlock.FACING);
 		if (!canBeStabilized(facing, pos.subtract(anchor))) {
 			BlockPos offset = pos.offset(facing);
@@ -440,7 +434,7 @@ public abstract class Contraption {
 		pendingSubContraptions.add(new BlockFace(pos, facing));
 	}
 
-	private void moveBelt(BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
+	private void moveBelt(BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited, BlockState state) {
 		BlockPos nextPos = BeltBlock.nextSegmentPosition(state, pos, true);
 		BlockPos prevPos = BeltBlock.nextSegmentPosition(state, pos, false);
 		if (nextPos != null && !visited.contains(nextPos))
@@ -461,7 +455,7 @@ public abstract class Contraption {
 		}
 	}
 
-	private void movePulley(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited) {
+	private void movePulley(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited) {
 		int limit = AllConfigs.SERVER.kinetics.maxRopeLength.get();
 		BlockPos ropePos = pos;
 		while (limit-- >= 0) {
@@ -479,8 +473,8 @@ public abstract class Contraption {
 		}
 	}
 
-	private boolean moveMechanicalPiston(World world, BlockPos pos, List<BlockPos> frontier, Set<BlockPos> visited,
+	private boolean moveMechanicalPiston(World world, BlockPos pos, Queue<BlockPos> frontier, Set<BlockPos> visited, BlockState state) throws AssemblyException {
-		BlockState state) {
+		int limit = AllConfigs.SERVER.kinetics.maxPistonPoles.get();
 		Direction direction = state.get(MechanicalPistonBlock.FACING);
 		PistonState pistonState = state.get(MechanicalPistonBlock.STATE);
 		if (pistonState == PistonState.MOVING)
@@ -503,7 +497,7 @@ public abstract class Contraption {
 		return true;
 	}
 
-	private boolean moveChassis(World world, BlockPos pos, Direction movementDirection, List<BlockPos> frontier,
+	private boolean moveChassis(World world, BlockPos pos, Direction movementDirection, Queue<BlockPos> frontier,
 		Set<BlockPos> visited) {
 		TileEntity te = world.getTileEntity(pos);
 		if (!(te instanceof ChassisTileEntity))
@@ -588,8 +582,8 @@ public abstract class Contraption {
 		return globalPos.subtract(anchor);
 	}
 
-	protected boolean movementAllowed(World world, BlockPos pos) {
+	protected boolean movementAllowed(BlockState state, World world, BlockPos pos) {
-		return BlockMovementTraits.movementAllowed(world, pos);
+		return BlockMovementTraits.movementAllowed(state, world, pos);
 	}
 
 	protected boolean isAnchoringBlockAt(BlockPos pos) {

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/IDisplayAssemblyExceptions.java

@@ -0,0 +1,28 @@
+package com.simibubi.create.content.contraptions.components.structureMovement;
+
+import com.simibubi.create.content.contraptions.goggles.IHaveGoggleInformation;
+import com.simibubi.create.foundation.utility.Lang;
+import net.minecraft.util.text.TextFormatting;
+
+import java.util.Arrays;
+import java.util.List;
+
+public interface IDisplayAssemblyExceptions {
+
+	default boolean addExceptionToTooltip(List<String> tooltip) {
+		AssemblyException e = getLastAssemblyException();
+		if (e == null)
+			return false;
+
+		if (!tooltip.isEmpty())
+			tooltip.add("");
+
+		tooltip.add(IHaveGoggleInformation.spacing + TextFormatting.GOLD + Lang.translate("gui.assembly.exception"));
+		String text = e.getFormattedText();
+		Arrays.stream(text.split("\n")).forEach(l -> tooltip.add(IHaveGoggleInformation.spacing + TextFormatting.GRAY + l));
+
+		return true;
+	}
+
+	AssemblyException getLastAssemblyException();
+}

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/BearingContraption.java

@@ -4,6 +4,7 @@ import org.apache.commons.lang3.tuple.Pair;
 
 import com.simibubi.create.AllTags.AllBlockTags;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 
 import net.minecraft.nbt.CompoundNBT;
@@ -28,7 +29,7 @@ public class BearingContraption extends Contraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		BlockPos offset = pos.offset(facing);
 		if (!searchMovedStructure(world, offset, null))
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/ClockworkBearingTileEntity.java

@@ -1,12 +1,10 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.bearing;
 
-import java.util.List;
-
-import org.apache.commons.lang3.tuple.Pair;
-
 import com.simibubi.create.content.contraptions.base.KineticTileEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.content.contraptions.components.structureMovement.bearing.ClockworkContraption.HandType;
 import com.simibubi.create.foundation.advancement.AllTriggers;
 import com.simibubi.create.foundation.gui.AllIcons;
@@ -16,7 +14,6 @@ import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOpt
 import com.simibubi.create.foundation.utility.AngleHelper;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.block.BlockState;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.state.properties.BlockStateProperties;
@@ -25,8 +22,12 @@ import net.minecraft.util.Direction;
 import net.minecraft.util.Direction.Axis;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
+import net.minecraft.util.text.ITextComponent;
+import org.apache.commons.lang3.tuple.Pair;
 
-public class ClockworkBearingTileEntity extends KineticTileEntity implements IBearingTileEntity {
+import java.util.List;
+
+public class ClockworkBearingTileEntity extends KineticTileEntity implements IBearingTileEntity, IDisplayAssemblyExceptions {
 
 	protected ControlledContraptionEntity hourHand;
 	protected ControlledContraptionEntity minuteHand;
@@ -37,6 +38,7 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 
 	protected boolean running;
 	protected boolean assembleNextTick;
+	protected AssemblyException lastException;
 
 	protected ScrollOptionBehaviour<ClockHands> operationMode;
 
@@ -105,6 +107,11 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		applyRotations();
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	protected void applyRotations() {
 		BlockState blockState = getBlockState();
 		Axis axis = Axis.X;
@@ -199,8 +206,15 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		Direction direction = getBlockState().get(BlockStateProperties.FACING);
 
 		// Collect Construct
-		Pair<ClockworkContraption, ClockworkContraption> contraption =
+		Pair<ClockworkContraption, ClockworkContraption> contraption;
-			ClockworkContraption.assembleClockworkAt(world, pos, direction);
+		try {
+			contraption = ClockworkContraption.assembleClockworkAt(world, pos, direction);
+			lastException = null;
+		} catch (AssemblyException e) {
+			lastException = e;
+			sendData();
+			return;
+		}
 		if (contraption == null)
 			return;
 		if (contraption.getLeft() == null)
@@ -284,6 +298,8 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		compound.putBoolean("Running", running);
 		compound.putFloat("HourAngle", hourAngle);
 		compound.putFloat("MinuteAngle", minuteAngle);
+		if (lastException != null)
+			compound.putString("LastException", ITextComponent.Serializer.toJson(lastException.component));
 		super.write(compound, clientPacket);
 	}
 
@@ -295,6 +311,10 @@ public class ClockworkBearingTileEntity extends KineticTileEntity implements IBe
 		running = compound.getBoolean("Running");
 		hourAngle = compound.getFloat("HourAngle");
 		minuteAngle = compound.getFloat("MinuteAngle");
+		if (compound.contains("LastException"))
+			lastException = new AssemblyException(ITextComponent.Serializer.fromJson(compound.getString("LastException")));
+		else
+			lastException = null;
 		super.read(compound, clientPacket);
 
 		if (!clientPacket)

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/ClockworkContraption.java

@@ -7,13 +7,18 @@ import java.util.Set;
 import org.apache.commons.lang3.tuple.Pair;
 
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 import com.simibubi.create.foundation.utility.NBTHelper;
-
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.world.World;
+import org.apache.commons.lang3.tuple.Pair;
+
+import java.util.HashSet;
+import java.util.Queue;
+import java.util.Set;
 
 public class ClockworkContraption extends Contraption {
 
@@ -38,7 +43,7 @@ public class ClockworkContraption extends Contraption {
 	}
 
 	public static Pair<ClockworkContraption, ClockworkContraption> assembleClockworkAt(World world, BlockPos pos,
-		Direction direction) {
+		Direction direction) throws AssemblyException {
 		int hourArmBlocks = 0;
 
 		ClockworkContraption hourArm = new ClockworkContraption();
@@ -81,21 +86,23 @@ public class ClockworkContraption extends Contraption {
 	}
 	
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		return searchMovedStructure(world, pos, facing);
 	}
 
 	@Override
-	public boolean searchMovedStructure(World world, BlockPos pos, Direction direction) {
+	public boolean searchMovedStructure(World world, BlockPos pos, Direction direction) throws AssemblyException {
 		return super.searchMovedStructure(world, pos.offset(direction, offset + 1), null);
 	}
 
 	@Override
-	protected boolean moveBlock(World world, BlockPos pos, Direction direction, List<BlockPos> frontier,
+	protected boolean moveBlock(World world, Direction direction, Queue<BlockPos> frontier,
-		Set<BlockPos> visited) {
+		Set<BlockPos> visited) throws AssemblyException {
-		if (ignoreBlocks.contains(pos))
+		if (ignoreBlocks.contains(frontier.peek())) {
+			frontier.poll();
 			return true;
-		return super.moveBlock(world, pos, direction, frontier, visited);
+		}
+		return super.moveBlock(world, direction, frontier, visited);
 	}
 
 	@Override

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/MechanicalBearingTileEntity.java

@@ -1,12 +1,10 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.bearing;
 
-import static net.minecraft.state.properties.BlockStateProperties.FACING;
-
-import java.util.List;
-
 import com.simibubi.create.content.contraptions.base.GeneratingKineticTileEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.foundation.advancement.AllTriggers;
 import com.simibubi.create.foundation.item.TooltipHelper;
 import com.simibubi.create.foundation.tileEntity.TileEntityBehaviour;
@@ -14,7 +12,6 @@ import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOpt
 import com.simibubi.create.foundation.utility.AngleHelper;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.block.BlockState;
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.state.properties.BlockStateProperties;
@@ -22,8 +19,13 @@ import net.minecraft.tileentity.TileEntityType;
 import net.minecraft.util.Direction;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
+import net.minecraft.util.text.ITextComponent;
 
-public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity implements IBearingTileEntity {
+import java.util.List;
+
+import static net.minecraft.state.properties.BlockStateProperties.FACING;
+
+public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity implements IBearingTileEntity, IDisplayAssemblyExceptions {
 
 	protected ScrollOptionBehaviour<RotationMode> movementMode;
 	protected ControlledContraptionEntity movedContraption;
@@ -31,6 +33,7 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 	protected boolean running;
 	protected boolean assembleNextTick;
 	protected float clientAngleDiff;
+	protected AssemblyException lastException;
 
 	public MechanicalBearingTileEntity(TileEntityType<? extends MechanicalBearingTileEntity> type) {
 		super(type);
@@ -62,6 +65,8 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 	public void write(CompoundNBT compound, boolean clientPacket) {
 		compound.putBoolean("Running", running);
 		compound.putFloat("Angle", angle);
+		if (lastException != null)
+			compound.putString("LastException", ITextComponent.Serializer.toJson(lastException.component));
 		super.write(compound, clientPacket);
 	}
 
@@ -70,6 +75,10 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 		float angleBefore = angle;
 		running = compound.getBoolean("Running");
 		angle = compound.getFloat("Angle");
+		if (compound.contains("LastException"))
+			lastException = new AssemblyException(ITextComponent.Serializer.fromJson(compound.getString("LastException")));
+		else
+			lastException = null;
 		super.read(compound, clientPacket);
 		if (!clientPacket)
 			return;
@@ -104,6 +113,11 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 		return speed;
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	protected boolean isWindmill() {
 		return false;
 	}
@@ -120,8 +134,16 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 
 		Direction direction = getBlockState().get(FACING);
 		BearingContraption contraption = new BearingContraption(isWindmill(), direction);
-		if (!contraption.assemble(world, pos))
+		try {
+			if (!contraption.assemble(world, pos))
+				return;
+
+			lastException = null;
+		} catch (AssemblyException e) {
+			lastException = e;
+			sendData();
 			return;
+		}
 
 		if (isWindmill())
 			AllTriggers.triggerForNearbyPlayers(AllTriggers.WINDMILL, world, pos, 5);
@@ -281,5 +303,4 @@ public class MechanicalBearingTileEntity extends GeneratingKineticTileEntity imp
 		TooltipHelper.addHint(tooltip, "hint.empty_bearing");
 		return true;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/bearing/StabilizedContraption.java

@@ -1,6 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.bearing;
 
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 
 import net.minecraft.nbt.CompoundNBT;
@@ -20,7 +21,7 @@ public class StabilizedContraption extends Contraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		BlockPos offset = pos.offset(facing);
 		if (!searchMovedStructure(world, offset, null))
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/chassis/ChassisTileEntity.java

@@ -7,6 +7,7 @@ import java.util.Collections;
 import java.util.HashSet;
 import java.util.LinkedList;
 import java.util.List;
+import java.util.Queue;
 import java.util.Set;
 
 import com.simibubi.create.AllBlocks;
@@ -76,12 +77,12 @@ public class ChassisTileEntity extends SmartTileEntity {
 	}
 
 	public List<ChassisTileEntity> collectChassisGroup() {
-		List<BlockPos> frontier = new ArrayList<>();
+		Queue<BlockPos> frontier = new LinkedList<>();
 		List<ChassisTileEntity> collected = new ArrayList<>();
 		Set<BlockPos> visited = new HashSet<>();
 		frontier.add(pos);
 		while (!frontier.isEmpty()) {
-			BlockPos current = frontier.remove(0);
+			BlockPos current = frontier.poll();
 			if (visited.contains(current))
 				continue;
 			visited.add(current);
@@ -96,7 +97,7 @@ public class ChassisTileEntity extends SmartTileEntity {
 		return collected;
 	}
 
-	public boolean addAttachedChasses(List<BlockPos> frontier, Set<BlockPos> visited) {
+	public boolean addAttachedChasses(Queue<BlockPos> frontier, Set<BlockPos> visited) {
 		BlockState state = getBlockState();
 		if (!(state.getBlock() instanceof AbstractChassisBlock))
 			return false;
@@ -166,7 +167,7 @@ public class ChassisTileEntity extends SmartTileEntity {
 					break;
 
 				// Ignore replaceable Blocks and Air-like
-				if (!BlockMovementTraits.movementNecessary(world, current))
+				if (!BlockMovementTraits.movementNecessary(currentState, world, current))
 					break;
 				if (BlockMovementTraits.isBrittle(currentState))
 					break;
@@ -207,7 +208,7 @@ public class ChassisTileEntity extends SmartTileEntity {
 					continue;
 				if (!searchPos.withinDistance(pos, chassisRange + .5f))
 					continue;
-				if (!BlockMovementTraits.movementNecessary(world, searchPos))
+				if (!BlockMovementTraits.movementNecessary(searchedState, world, searchPos))
 					continue;
 				if (BlockMovementTraits.isBrittle(searchedState))
 					continue;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/glue/SuperGlueEntity.java

@@ -180,7 +180,7 @@ public class SuperGlueEntity extends Entity implements IEntityAdditionalSpawnDat
 		BlockState state = world.getBlockState(pos);
 		if (BlockMovementTraits.isBlockAttachedTowards(world, pos, state, direction))
 			return true;
-		if (!BlockMovementTraits.movementNecessary(world, pos))
+		if (!BlockMovementTraits.movementNecessary(state, world, pos))
 			return false;
 		if (BlockMovementTraits.notSupportive(state, direction))
 			return false;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/CartAssemblerBlock.java

@@ -3,6 +3,7 @@ package com.simibubi.create.content.contraptions.components.structureMovement.mo
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllShapes;
 import com.simibubi.create.AllTileEntities;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.OrientedContraptionEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.mounted.CartAssemblerTileEntity.CartMovementMode;
 import com.simibubi.create.content.contraptions.components.structureMovement.train.CouplingHandler;
@@ -229,13 +230,27 @@ public class CartAssemblerBlock extends AbstractRailBlock
 			.isCoupledThroughContraption())
 			return;
 
-		CartMovementMode mode =
+		
-			getTileEntityOptional(world, pos).map(te -> CartMovementMode.values()[te.movementMode.value])
+		Optional<CartAssemblerTileEntity> assembler = getTileEntityOptional(world, pos);
+		CartMovementMode mode = assembler.map(te -> CartMovementMode.values()[te.movementMode.value])
 				.orElse(CartMovementMode.ROTATE);
 
 		MountedContraption contraption = new MountedContraption(mode);
-		if (!contraption.assemble(world, pos))
+		try {
+			if (!contraption.assemble(world, pos))
+				return;
+
+			assembler.ifPresent(te -> {
+				te.lastException = null;
+				te.sendData();
+			});
+		} catch (AssemblyException e) {
+			assembler.ifPresent(te -> {
+				te.lastException = e;
+				te.sendData();
+			});
 			return;
+		}
 
 		boolean couplingFound = contraption.connectedCart != null;
 		Optional<Direction> initialOrientation = cart.getMotion()

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/CartAssemblerTileEntity.java

@@ -1,7 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.mounted;
 
-import java.util.List;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
-
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.foundation.gui.AllIcons;
 import com.simibubi.create.foundation.tileEntity.SmartTileEntity;
 import com.simibubi.create.foundation.tileEntity.TileEntityBehaviour;
@@ -11,17 +11,21 @@ import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.INamedIco
 import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOptionBehaviour;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.VecHelper;
-
+import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.state.properties.RailShape;
 import net.minecraft.tileentity.TileEntityType;
 import net.minecraft.util.Direction.Axis;
 import net.minecraft.util.math.Vec3d;
+import net.minecraft.util.text.ITextComponent;
 
-public class CartAssemblerTileEntity extends SmartTileEntity {
+import java.util.List;
+
+public class CartAssemblerTileEntity extends SmartTileEntity implements IDisplayAssemblyExceptions {
 	private static final int assemblyCooldown = 8;
 
 	protected ScrollOptionBehaviour<CartMovementMode> movementMode;
 	private int ticksSinceMinecartUpdate;
+	protected AssemblyException lastException;
 
 	public CartAssemblerTileEntity(TileEntityType<? extends CartAssemblerTileEntity> type) {
 		super(type);
@@ -44,6 +48,27 @@ public class CartAssemblerTileEntity extends SmartTileEntity {
 		behaviours.add(movementMode);
 	}
 
+	@Override
+	public void write(CompoundNBT compound, boolean clientPacket) {
+		if (lastException != null)
+			compound.putString("LastException", ITextComponent.Serializer.toJson(lastException.component));
+		super.write(compound, clientPacket);
+	}
+
+	@Override
+	protected void read(CompoundNBT compound, boolean clientPacket) {
+		if (compound.contains("LastException"))
+			lastException = new AssemblyException(ITextComponent.Serializer.fromJson(compound.getString("LastException")));
+		else
+			lastException = null;
+		super.read(compound, clientPacket);
+	}
+
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	protected ValueBoxTransform getMovementModeSlot() {
 		return new CartAssemblerValueBoxTransform();
 	}
@@ -103,5 +128,4 @@ public class CartAssemblerTileEntity extends SmartTileEntity {
 	public boolean isMinecartUpdateValid() {
 		return ticksSinceMinecartUpdate >= assemblyCooldown;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/mounted/MountedContraption.java

@@ -2,12 +2,13 @@ package com.simibubi.create.content.contraptions.components.structureMovement.mo
 
 import static com.simibubi.create.content.contraptions.components.structureMovement.mounted.CartAssemblerBlock.RAIL_SHAPE;
 
-import java.util.List;
+import java.util.Queue;
 
 import org.apache.commons.lang3.tuple.Pair;
 
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.Contraption;
 import com.simibubi.create.content.contraptions.components.structureMovement.mounted.CartAssemblerTileEntity.CartMovementMode;
 import com.simibubi.create.foundation.utility.Iterate;
@@ -52,7 +53,7 @@ public class MountedContraption extends Contraption {
 	}
 	
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		BlockState state = world.getBlockState(pos);
 		if (!state.has(RAIL_SHAPE))
 			return false;
@@ -70,7 +71,7 @@ public class MountedContraption extends Contraption {
 	}
 	
 	@Override
-	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, List<BlockPos> frontier) {
+	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, Queue<BlockPos> frontier) {
 		frontier.clear();
 		frontier.add(pos.up());
 		return true;
@@ -104,11 +105,10 @@ public class MountedContraption extends Contraption {
 	}
 
 	@Override
-	protected boolean movementAllowed(World world, BlockPos pos) {
+	protected boolean movementAllowed(BlockState state, World world, BlockPos pos) {
-		BlockState blockState = world.getBlockState(pos);
+		if (!pos.equals(anchor) && AllBlocks.CART_ASSEMBLER.has(state))
-		if (!pos.equals(anchor) && AllBlocks.CART_ASSEMBLER.has(blockState))
+			return testSecondaryCartAssembler(world, state, pos);
-			return testSecondaryCartAssembler(world, blockState, pos);
+		return super.movementAllowed(state, world, pos);
-		return super.movementAllowed(world, pos);
 	}
 
 	protected boolean testSecondaryCartAssembler(World world, BlockState state, BlockPos pos) {

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/LinearActuatorTileEntity.java

@@ -1,24 +1,22 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.piston;
 
-import java.util.List;
-
 import com.simibubi.create.content.contraptions.base.KineticTileEntity;
-import com.simibubi.create.content.contraptions.components.structureMovement.AbstractContraptionEntity;
+import com.simibubi.create.content.contraptions.components.structureMovement.*;
-import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
-import com.simibubi.create.content.contraptions.components.structureMovement.IControlContraption;
 import com.simibubi.create.foundation.tileEntity.TileEntityBehaviour;
 import com.simibubi.create.foundation.tileEntity.behaviour.ValueBoxTransform;
 import com.simibubi.create.foundation.tileEntity.behaviour.scrollvalue.ScrollOptionBehaviour;
 import com.simibubi.create.foundation.utility.Lang;
 import com.simibubi.create.foundation.utility.ServerSpeedProvider;
-
 import net.minecraft.nbt.CompoundNBT;
 import net.minecraft.tileentity.TileEntityType;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
+import net.minecraft.util.text.ITextComponent;
 
-public abstract class LinearActuatorTileEntity extends KineticTileEntity implements IControlContraption {
+import java.util.List;
+
+public abstract class LinearActuatorTileEntity extends KineticTileEntity implements IControlContraption, IDisplayAssemblyExceptions {
 
 	public float offset;
 	public boolean running;
@@ -27,6 +25,7 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 	protected boolean forceMove;
 	protected ScrollOptionBehaviour<MovementMode> movementMode;
 	protected boolean waitingForSpeedChange;
+	protected AssemblyException lastException;
 
 	// Custom position sync
 	protected float clientOffsetDiff;
@@ -80,7 +79,13 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 				return;
 			} else {
 				if (getSpeed() != 0)
-					assemble();
+					try {
+						assemble();
+						lastException = null;
+					} catch (AssemblyException e) {
+						lastException = e;
+					}
+				sendData();
 			}
 			return;
 		}
@@ -153,6 +158,8 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 		compound.putBoolean("Running", running);
 		compound.putBoolean("Waiting", waitingForSpeedChange);
 		compound.putFloat("Offset", offset);
+		if (lastException != null)
+			compound.putString("LastException", ITextComponent.Serializer.toJson(lastException.component));
 		super.write(compound, clientPacket);
 
 		if (clientPacket && forceMove) {
@@ -169,6 +176,10 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 		running = compound.getBoolean("Running");
 		waitingForSpeedChange = compound.getBoolean("Waiting");
 		offset = compound.getFloat("Offset");
+		if (compound.contains("LastException"))
+			lastException = new AssemblyException(ITextComponent.Serializer.fromJson(compound.getString("LastException")));
+		else
+			lastException = null;
 		super.read(compound, clientPacket);
 
 		if (!clientPacket)
@@ -183,9 +194,14 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 			movedContraption = null;
 	}
 
+	@Override
+	public AssemblyException getLastAssemblyException() {
+		return lastException;
+	}
+
 	public abstract void disassemble();
 
-	protected abstract void assemble();
+	protected abstract void assemble() throws AssemblyException;
 
 	protected abstract int getExtensionRange();
 
@@ -288,5 +304,4 @@ public abstract class LinearActuatorTileEntity extends KineticTileEntity impleme
 	public BlockPos getBlockPosition() {
 		return pos;
 	}
-
 }

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/MechanicalPistonTileEntity.java

@@ -2,6 +2,7 @@ package com.simibubi.create.content.contraptions.components.structureMovement.pi
 
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.content.contraptions.base.IRotate;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionCollider;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
 import com.simibubi.create.content.contraptions.components.structureMovement.DirectionalExtenderScrollOptionSlot;
@@ -41,7 +42,7 @@ public class MechanicalPistonTileEntity extends LinearActuatorTileEntity {
 	}
 
 	@Override
-	public void assemble() {
+	public void assemble() throws AssemblyException {
 		if (!(world.getBlockState(pos)
 			.getBlock() instanceof MechanicalPistonBlock))
 			return;

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/piston/PistonContraption.java

@@ -1,6 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.piston;
 
-import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
+import com.simibubi.create.content.contraptions.components.structureMovement.AllContraptionTypes;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.BlockMovementTraits;
 import com.simibubi.create.content.contraptions.components.structureMovement.TranslatingContraption;
 import com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock.*;
@@ -23,6 +24,7 @@ import org.apache.commons.lang3.tuple.Pair;
 
 import java.util.ArrayList;
 import java.util.List;
+import java.util.Queue;
 
 import static com.simibubi.create.AllBlocks.MECHANICAL_PISTON_HEAD;
 import static com.simibubi.create.AllBlocks.PISTON_EXTENSION_POLE;
@@ -51,7 +53,7 @@ public class PistonContraption extends TranslatingContraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		if (!collectExtensions(world, pos, orientation))
 			return false;
 		int count = blocks.size();
@@ -66,7 +68,7 @@ public class PistonContraption extends TranslatingContraption {
 		return true;
 	}
 
-	private boolean collectExtensions(World world, BlockPos pos, Direction direction) {
+	private boolean collectExtensions(World world, BlockPos pos, Direction direction) throws AssemblyException {
 		List<BlockInfo> poles = new ArrayList<>();
 		BlockPos actualStart = pos;
 		BlockState nextBlock = world.getBlockState(actualStart.offset(direction));
@@ -89,7 +91,7 @@ public class PistonContraption extends TranslatingContraption {
 
 				nextBlock = world.getBlockState(actualStart.offset(direction));
 				if (extensionsInFront > MechanicalPistonBlock.maxAllowedPistonPoles())
-					return false;
+					throw AssemblyException.tooManyPistonPoles();
 			}
 		}
 
@@ -112,7 +114,7 @@ public class PistonContraption extends TranslatingContraption {
 			nextBlock = world.getBlockState(end.offset(direction.getOpposite()));
 
 			if (extensionsInFront + extensionsInBack > MechanicalPistonBlock.maxAllowedPistonPoles())
-				return false;
+				throw AssemblyException.tooManyPistonPoles();
 		}
 
 		anchor = pos.offset(direction, initialExtensionProgress + 1);
@@ -124,7 +126,7 @@ public class PistonContraption extends TranslatingContraption {
 						1, 1);
 
 		if (extensionLength == 0)
-			return false;
+			throw AssemblyException.noPistonPoles();
 
 		bounds = new AxisAlignedBB(0, 0, 0, 0, 0, 0);
 
@@ -144,7 +146,7 @@ public class PistonContraption extends TranslatingContraption {
 	}
 
 	@Override
-	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, List<BlockPos> frontier) {
+	protected boolean addToInitialFrontier(World world, BlockPos pos, Direction direction, Queue<BlockPos> frontier) throws AssemblyException {
 		frontier.clear();
 		boolean sticky = isStickyPiston(world.getBlockState(pos.offset(orientation, -1)));
 		boolean retracting = direction != orientation;
@@ -154,17 +156,22 @@ public class PistonContraption extends TranslatingContraption {
 			if (offset == 1 && retracting)
 				return true;
 			BlockPos currentPos = pos.offset(orientation, offset + initialExtensionProgress);
-			if (!world.isBlockPresent(currentPos))
+			if (retracting && World.isOutsideBuildHeight(currentPos))
-				return false;
-			if (!BlockMovementTraits.movementNecessary(world, currentPos))
 				return true;
+			if (!world.isBlockPresent(currentPos))
+				throw AssemblyException.unloadedChunk(currentPos);
 			BlockState state = world.getBlockState(currentPos);
+			if (!BlockMovementTraits.movementNecessary(state, world, currentPos))
+				return true;
 			if (BlockMovementTraits.isBrittle(state) && !(state.getBlock() instanceof CarpetBlock))
 				return true;
 			if (isPistonHead(state) && state.get(FACING) == direction.getOpposite())
 				return true;
-			if (!BlockMovementTraits.movementAllowed(world, currentPos))
+			if (!BlockMovementTraits.movementAllowed(state, world, currentPos))
-				return retracting;
+				if (retracting)
+					return true;
+				else
+					throw AssemblyException.unmovableBlock(currentPos, state);
 			if (retracting && state.getPushReaction() == PushReaction.PUSH_ONLY)
 				return true;
 			frontier.add(currentPos);

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/pulley/PulleyContraption.java

@@ -1,5 +1,6 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.pulley;
 
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionType;
 import com.simibubi.create.content.contraptions.components.structureMovement.TranslatingContraption;
 
@@ -23,7 +24,7 @@ public class PulleyContraption extends TranslatingContraption {
 	}
 
 	@Override
-	public boolean assemble(World world, BlockPos pos) {
+	public boolean assemble(World world, BlockPos pos) throws AssemblyException {
 		if (!searchMovedStructure(world, pos, null))
 			return false;
 		startMoving(world);

src/main/java/com/simibubi/create/content/contraptions/components/structureMovement/pulley/PulleyTileEntity.java

@@ -1,6 +1,7 @@
 package com.simibubi.create.content.contraptions.components.structureMovement.pulley;
 
 import com.simibubi.create.AllBlocks;
+import com.simibubi.create.content.contraptions.components.structureMovement.AssemblyException;
 import com.simibubi.create.content.contraptions.components.structureMovement.BlockMovementTraits;
 import com.simibubi.create.content.contraptions.components.structureMovement.ContraptionCollider;
 import com.simibubi.create.content.contraptions.components.structureMovement.ControlledContraptionEntity;
@@ -8,7 +9,6 @@ import com.simibubi.create.content.contraptions.components.structureMovement.pis
 import com.simibubi.create.foundation.config.AllConfigs;
 import com.simibubi.create.foundation.tileEntity.behaviour.CenteredSideValueBoxTransform;
 import com.simibubi.create.foundation.tileEntity.behaviour.ValueBoxTransform;
-
 import net.minecraft.block.BlockState;
 import net.minecraft.block.Blocks;
 import net.minecraft.block.IWaterLoggable;
@@ -22,6 +22,7 @@ import net.minecraft.util.math.AxisAlignedBB;
 import net.minecraft.util.math.BlockPos;
 import net.minecraft.util.math.MathHelper;
 import net.minecraft.util.math.Vec3d;
+import net.minecraft.util.text.ITextComponent;
 
 public class PulleyTileEntity extends LinearActuatorTileEntity {
 
@@ -42,7 +43,7 @@ public class PulleyTileEntity extends LinearActuatorTileEntity {
 	}
 
 	@Override
-	protected void assemble() {
+	protected void assemble() throws AssemblyException {
 		if (!(world.getBlockState(pos)
 			.getBlock() instanceof PulleyBlock))
 			return;
@@ -176,9 +177,10 @@ public class PulleyTileEntity extends LinearActuatorTileEntity {
 			return;
 
 		BlockPos posBelow = pos.down((int) (offset + getMovementSpeed()) + 1);
-		if (!BlockMovementTraits.movementNecessary(world, posBelow))
+		BlockState state = world.getBlockState(posBelow);
+		if (!BlockMovementTraits.movementNecessary(state, world, posBelow))
 			return;
-		if (BlockMovementTraits.isBrittle(world.getBlockState(posBelow)))
+		if (BlockMovementTraits.isBrittle(state))
 			return;
 
 		disassemble();
@@ -188,12 +190,18 @@ public class PulleyTileEntity extends LinearActuatorTileEntity {
 	@Override
 	protected void read(CompoundNBT compound, boolean clientPacket) {
 		initialOffset = compound.getInt("InitialOffset");
+		if (compound.contains("LastException"))
+			lastException = new AssemblyException(ITextComponent.Serializer.fromJson(compound.getString("LastException")));
+		else
+			lastException = null;
 		super.read(compound, clientPacket);
 	}
 
 	@Override
 	public void write(CompoundNBT compound, boolean clientPacket) {
 		compound.putInt("InitialOffset", initialOffset);
+		if (lastException != null)
+			compound.putString("LastException", ITextComponent.Serializer.toJson(lastException.component));
 		super.write(compound, clientPacket);
 	}
 

src/main/java/com/simibubi/create/content/contraptions/goggles/GoggleOverlayRenderer.java

@@ -4,6 +4,7 @@ import com.mojang.blaze3d.systems.RenderSystem;
 import com.simibubi.create.AllBlocks;
 import com.simibubi.create.AllItems;
 import com.simibubi.create.CreateClient;
+import com.simibubi.create.content.contraptions.components.structureMovement.IDisplayAssemblyExceptions;
 import com.simibubi.create.content.contraptions.components.structureMovement.piston.MechanicalPistonBlock;
 import com.simibubi.create.content.contraptions.components.structureMovement.piston.PistonExtensionPoleBlock;
 import com.simibubi.create.foundation.config.AllConfigs;
@@ -92,6 +93,14 @@ public class GoggleOverlayRenderer {
 				tooltip.remove(tooltip.size() - 1);
 		}
 
+		if (te instanceof IDisplayAssemblyExceptions) {
+			boolean exceptionAdded = ((IDisplayAssemblyExceptions) te).addExceptionToTooltip(tooltip);
+			if (exceptionAdded) {
+				hasHoveringInformation = true;
+				hoverAddedInformation = true;
+			}
+		}
+
 		// break early if goggle or hover returned false when present
 		if ((hasGoggleInformation && !goggleAddedInformation) && (hasHoveringInformation && !hoverAddedInformation))
 			return;

src/main/java/com/simibubi/create/content/contraptions/goggles/IHaveGoggleInformation.java

@@ -9,13 +9,13 @@ import java.util.List;
 public interface IHaveGoggleInformation {
 
 	DecimalFormat decimalFormat = new DecimalFormat("#.##");
-	public static String spacing = "    ";
+	String spacing = "    ";
 
 	/**
 	* this method will be called when looking at a TileEntity that implemented this interface
 	 *
-	 * @return {{@code true}} if the tooltip creation was successful and should be displayed,
+	 * @return {@code true} if the tooltip creation was successful and should be displayed,
-	 * or {{@code false}} if the overlay should not be displayed
+	 * or {@code false} if the overlay should not be displayed
 	* */
 	default boolean addToGoggleTooltip(List<String> tooltip, boolean isPlayerSneaking){
 		return false;

src/main/resources/assets/create/lang/default/messages.json

@@ -172,6 +172,13 @@
 	"create.gui.goggles.at_current_speed": "at current speed",
 	"create.gui.goggles.pole_length": "Pole Length:",
 
+	"create.gui.assembly.exception": "This Contraption was unable to assemble:",
+	"create.gui.assembly.exception.unmovableBlock": "Unmovable Block (%4$s) at [%1$s %2$s %3$s]",
+	"create.gui.assembly.exception.chunkNotLoaded": "The Block at [%1$s %2$s %3$s] was not in a loaded chunk",
+	"create.gui.assembly.exception.structureTooLarge": "There are too many Blocks included in the contraption.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.tooManyPistonPoles": "There are too many extension Poles attached to this Piston.\nThe configured maximum is: %1$s",
+	"create.gui.assembly.exception.noPistonPoles": "The Piston is missing some extension Poles",
+
 	"create.gui.gauge.info_header": "Gauge Information:",
 	"create.gui.speedometer.title": "Rotation Speed",
 	"create.gui.stressometer.title": "Network Stress",