Paper/nms-patches/DataPaletteBlock.patch

--- a/net/minecraft/server/DataPaletteBlock.java
+++ b/net/minecraft/server/DataPaletteBlock.java
@@ -109,7 +109,21 @@
             int i1 = nibblearray1 == null ? 0 : nibblearray1.a(j, k, l);
             int j1 = i1 << 12 | (abyte[i] & 255) << 4 | nibblearray.a(j, k, l);
 
-            this.setBlockIndex(i, (IBlockData) Block.REGISTRY_ID.fromId(j1));
+            // CraftBukkit start - fix blocks with random data values (caused by plugins)
+            IBlockData data = Block.REGISTRY_ID.fromId(j1);
+            if (data == null) {
+                Block block = Block.getById(j1 >> 4);
+                if (block != null) {
+                    try {
+                        data = block.fromLegacyData(j1 & 0xF);
+                    } catch (Exception ignored) {
+                        data = block.getBlockData();
+                    }
+                }
+            }
+            this.setBlockIndex(i, data);
+            // this.setBlockIndex(i, (IBlockData) Block.REGISTRY_ID.fromId(j1));
+            // CraftBukkit end
         }
 
     }
@@ -117,6 +131,6 @@
     public int a() {
         int i = this.b.b();
 
-        return 1 + this.c.a() + PacketDataSerializer.a(i) + i * 8;
+        return 1 + this.c.a() + PacketDataSerializer.a(i) + this.b.a().length * 8; // CraftBukkit - Backport fix, remove on update
     }
 }