WORLDEDIT-2857 - Reported by Puseidr

Spigot: #1031 (1.6.2)
WorldEdit: 5.5.7

2013-07-13 23:23:34 [SEVERE] Block at -336,29,-440 is HOPPER but has net.minecraft.server.v1_6_R2.TileEntityDropper@575a39d4. Bukkit will attempt to fix this, but there may be additional damage that we cannot recover.
2013-07-13 23:23:34 [SEVERE] java.lang.ClassCastException: net.minecraft.server.v1_6_R2.TileEntityHopper cannot be cast to net.minecraft.server.v1_6_R2.TileEntityDispenser
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.BlockDispenser.remove(BlockDispenser.java:128)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.Chunk.a(Chunk.java:390)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.World.setTypeIdAndData(World.java:332)
2013-07-13 23:23:34 [SEVERE] at org.bukkit.craftbukkit.v1_6_R2.block.CraftBlock.setTypeIdAndData(CraftBlock.java:121)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.bukkit.BukkitWorld.setTypeIdAndData(BukkitWorld.java:304)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.LocalWorld.setBlock(LocalWorld.java:537)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.bukkit.BukkitWorld.setBlock(BukkitWorld.java:1353)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.EditSession.rawSetBlock(EditSession.java:237)
2013-07-13 23:23:34 [SEVERE] at net.coreprotect.worldedit.CoreProtectEditSession.rawSetBlock(CoreProtectEditSession.java:39)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.EditSession.flushQueue(EditSession.java:707)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.WorldEdit.handleCommand(WorldEdit.java:1413)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.worldedit.bukkit.WorldEditPlugin.onCommand(WorldEditPlugin.java:242)
2013-07-13 23:23:34 [SEVERE] at com.sk89q.bukkit.util.DynamicPluginCommand.execute(DynamicPluginCommand.java:52)
2013-07-13 23:23:34 [SEVERE] at org.bukkit.command.SimpleCommandMap.dispatch(SimpleCommandMap.java:190)
2013-07-13 23:23:34 [SEVERE] at org.bukkit.craftbukkit.v1_6_R2.CraftServer.dispatchCommand(CraftServer.java:527)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.PlayerConnection.handleCommand(PlayerConnection.java:981)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.PlayerConnection.chat(PlayerConnection.java:892)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.PlayerConnection.a(PlayerConnection.java:839)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.Packet3Chat.handle(SourceFile:49)
2013-07-13 23:23:34 [SEVERE] at org.spigotmc.netty.NettyNetworkManager.b(NettyNetworkManager.java:235)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.PlayerConnection.e(PlayerConnection.java:118)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.ServerConnection.b(SourceFile:37)
2013-07-13 23:23:34 [SEVERE] at org.spigotmc.netty.NettyServerConnection.b(NettyServerConnection.java:125)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.MinecraftServer.t(MinecraftServer.java:592)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.DedicatedServer.t(DedicatedServer.java:239)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.MinecraftServer.s(MinecraftServer.java:481)
2013-07-13 23:23:34 [SEVERE] at net.minecraft.server.v1_6_R2.MinecraftServer.run(MinecraftServer.java:413)

Comment by sk89q

Please post the contents of

/version
/we version

And try the latest version of WE from
http://builds.enginehub.org/job/worldedit/last-successful/?branch=master