--- a/net/minecraft/server/level/ChunkHolder.java
+++ b/net/minecraft/server/level/ChunkHolder.java
@@ -28,6 +28,10 @@
 import net.minecraft.world.level.chunk.status.ChunkStatus;
 import net.minecraft.world.level.lighting.LevelLightEngine;
 
+// CraftBukkit start
+import net.minecraft.server.MinecraftServer;
+// CraftBukkit end
+
 public class ChunkHolder extends GenerationChunkHolder {
 
     public static final ChunkResult<LevelChunk> UNLOADED_LEVEL_CHUNK = ChunkResult.error("Unloaded level chunk");
@@ -58,9 +62,9 @@
         this.entityTickingChunkFuture = ChunkHolder.UNLOADED_LEVEL_CHUNK_FUTURE;
         this.blockChangedLightSectionFilter = new BitSet();
         this.skyChangedLightSectionFilter = new BitSet();
-        this.pendingFullStateConfirmation = CompletableFuture.completedFuture((Object) null);
-        this.sendSync = CompletableFuture.completedFuture((Object) null);
-        this.saveSync = CompletableFuture.completedFuture((Object) null);
+        this.pendingFullStateConfirmation = CompletableFuture.completedFuture(null); // CraftBukkit - decompile error
+        this.sendSync = CompletableFuture.completedFuture(null); // CraftBukkit - decompile error
+        this.saveSync = CompletableFuture.completedFuture(null); // CraftBukkit - decompile error
         this.levelHeightAccessor = world;
         this.lightEngine = lightingProvider;
         this.onLevelChange = levelUpdateListener;
@@ -70,7 +74,19 @@
         this.queueLevel = this.oldTicketLevel;
         this.setTicketLevel(level);
         this.changedBlocksPerSection = new ShortSet[world.getSectionsCount()];
+    }
+
+    // CraftBukkit start
+    public LevelChunk getFullChunkNow() {
+        // Note: We use the oldTicketLevel for isLoaded checks.
+        if (!ChunkLevel.fullStatus(this.oldTicketLevel).isOrAfter(FullChunkStatus.FULL)) return null;
+        return this.getFullChunkNowUnchecked();
+    }
+
+    public LevelChunk getFullChunkNowUnchecked() {
+        return (LevelChunk) this.getChunkIfPresentUnchecked(ChunkStatus.FULL);
     }
+    // CraftBukkit end
 
     public CompletableFuture<ChunkResult<LevelChunk>> getTickingChunkFuture() {
         return this.tickingChunkFuture;
@@ -86,7 +102,7 @@
 
     @Nullable
     public LevelChunk getTickingChunk() {
-        return (LevelChunk) ((ChunkResult) this.getTickingChunkFuture().getNow(ChunkHolder.UNLOADED_LEVEL_CHUNK)).orElse((Object) null);
+        return (LevelChunk) ((ChunkResult) this.getTickingChunkFuture().getNow(ChunkHolder.UNLOADED_LEVEL_CHUNK)).orElse(null); // CraftBukkit - decompile error
     }
 
     @Nullable
@@ -138,6 +154,7 @@
             boolean flag = this.hasChangedSections;
             int i = this.levelHeightAccessor.getSectionIndex(pos.getY());
 
+            if (i < 0 || i >= this.changedBlocksPerSection.length) return false; // CraftBukkit - SPIGOT-6086, SPIGOT-6296
             if (this.changedBlocksPerSection[i] == null) {
                 this.hasChangedSections = true;
                 this.changedBlocksPerSection[i] = new ShortOpenHashSet();
@@ -224,8 +241,11 @@
                                 ClientboundSectionBlocksUpdatePacket packetplayoutmultiblockchange = new ClientboundSectionBlocksUpdatePacket(sectionposition, shortset, chunksection);
 
                                 this.broadcast(list, packetplayoutmultiblockchange);
+                                // CraftBukkit start
+                                List finalList = list;
                                 packetplayoutmultiblockchange.runUpdates((blockposition1, iblockdata1) -> {
-                                    this.broadcastBlockEntityIfNeeded(list, world, blockposition1, iblockdata1);
+                                    this.broadcastBlockEntityIfNeeded(finalList, world, blockposition1, iblockdata1);
+                                    // CraftBukkit end
                                 });
                             }
                         }
@@ -291,7 +311,7 @@
         this.pendingFullStateConfirmation = completablefuture1;
         chunkFuture.thenAccept((chunkresult) -> {
             chunkresult.ifSuccess((chunk) -> {
-                completablefuture1.complete((Object) null);
+                completablefuture1.complete(null); // CraftBukkit - decompile error
             });
         });
     }
@@ -299,7 +319,39 @@
     private void demoteFullChunk(ChunkMap chunkLoadingManager, FullChunkStatus target) {
         this.pendingFullStateConfirmation.cancel(false);
         chunkLoadingManager.onFullChunkStatusChange(this.pos, target);
+    }
+
+    // CraftBukkit start
+    // ChunkUnloadEvent: Called before the chunk is unloaded: isChunkLoaded is still true and chunk can still be modified by plugins.
+    // SPIGOT-7780: Moved out of updateFutures to call all chunk unload events before calling updateHighestAllowedStatus for all chunks
+    protected void callEventIfUnloading(ChunkMap playerchunkmap) {
+        FullChunkStatus oldFullChunkStatus = ChunkLevel.fullStatus(this.oldTicketLevel);
+        FullChunkStatus newFullChunkStatus = ChunkLevel.fullStatus(this.ticketLevel);
+        boolean oldIsFull = oldFullChunkStatus.isOrAfter(FullChunkStatus.FULL);
+        boolean newIsFull = newFullChunkStatus.isOrAfter(FullChunkStatus.FULL);
+        if (oldIsFull && !newIsFull) {
+            this.getFullChunkFuture().thenAccept((either) -> {
+                LevelChunk chunk = (LevelChunk) either.orElse(null);
+                if (chunk != null) {
+                    playerchunkmap.callbackExecutor.execute(() -> {
+                        // Minecraft will apply the chunks tick lists to the world once the chunk got loaded, and then store the tick
+                        // lists again inside the chunk once the chunk becomes inaccessible and set the chunk's needsSaving flag.
+                        // These actions may however happen deferred, so we manually set the needsSaving flag already here.
+                        chunk.markUnsaved();
+                        chunk.unloadCallback();
+                    });
+                }
+            }).exceptionally((throwable) -> {
+                // ensure exceptions are printed, by default this is not the case
+                MinecraftServer.LOGGER.error("Failed to schedule unload callback for chunk " + ChunkHolder.this.pos, throwable);
+                return null;
+            });
+
+            // Run callback right away if the future was already done
+            playerchunkmap.callbackExecutor.run();
+        }
     }
+    // CraftBukkit end
 
     protected void updateFutures(ChunkMap chunkLoadingManager, Executor executor) {
         FullChunkStatus fullchunkstatus = ChunkLevel.fullStatus(this.oldTicketLevel);
@@ -357,6 +409,26 @@
 
         this.onLevelChange.onLevelChange(this.pos, this::getQueueLevel, this.ticketLevel, this::setQueueLevel);
         this.oldTicketLevel = this.ticketLevel;
+        // CraftBukkit start
+        // ChunkLoadEvent: Called after the chunk is loaded: isChunkLoaded returns true and chunk is ready to be modified by plugins.
+        if (!fullchunkstatus.isOrAfter(FullChunkStatus.FULL) && fullchunkstatus1.isOrAfter(FullChunkStatus.FULL)) {
+            this.getFullChunkFuture().thenAccept((either) -> {
+                LevelChunk chunk = (LevelChunk) either.orElse(null);
+                if (chunk != null) {
+                    chunkLoadingManager.callbackExecutor.execute(() -> {
+                        chunk.loadCallback();
+                    });
+                }
+            }).exceptionally((throwable) -> {
+                // ensure exceptions are printed, by default this is not the case
+                MinecraftServer.LOGGER.error("Failed to schedule load callback for chunk " + ChunkHolder.this.pos, throwable);
+                return null;
+            });
+
+            // Run callback right away if the future was already done
+            chunkLoadingManager.callbackExecutor.run();
+        }
+        // CraftBukkit end
     }
 
     public boolean wasAccessibleSinceLastSave() {