i can't understand this error

[AvaritiaPM]

HandshakeMessageHandler exception

java.lang.VerifyError: Bad type on operand stack

Exception Details:

Location:

net/minecraft/network/NetHandlerPlayServer.func_147340_a(Lnet/minecraft/network/play/client/CPacketUseEntity;)V @350: invokeinterface

Reason:

Type 'java/lang/Object' (current frame, stack[1]) is not assignable to 'org/bukkit/event/Event'

Current Frame:

bci: @350

flags: { }

locals: { 'net/minecraft/network/NetHandlerPlayServer', 'net/minecraft/network/play/client/CPacketUseEntity', 'net/minecraft/world/WorldServer', 'net/minecraft/entity/Entity', integer, double, double_2nd, 'net/minecraft/item/ItemStack', integer, 'net/minecraft/item/Item', 'java/lang/Object' }

stack: { 'org/bukkit/plugin/PluginManager', 'java/lang/Object' }

Bytecode:

0x0000000: 2b2a 2ab4 00e9 b602 24b8 022a 2ab4 00e9

0x0000010: b603 3c99 0004 b12a b400 df2a b400 e9b4

0x0000020: 0407 b604 0b4d 2b2c b608 dd4e 2d2a b400

0x0000030: e9a6 0015 2ab4 00e9 b604 e69a 000b 2a13

0x0000040: 08df b601 c4b1 2ab4 00e9 b601 a52d c602

0x0000050: bb2a b400 e92d b608 e336 0414 08e4 3905

0x0000060: 1504 9a00 0814 08e6 3905 2ab4 00e9 2db6

0x0000070: 08eb 1805 989c 0294 2ab4 00e9 2bb6 08ee

0x0000080: c700 09b2 04fb a700 072b b608 eeb6 04f0

0x0000090: 3a07 2bb6 08f2 b208 f6a5 000d 2bb6 08f2

0x00000a0: b208 f9a6 0144 1907 c600 1919 07b6 08bc

0x00000b0: b208 fca6 000e 2dc1 08fe 9900 0704 a700

0x00000c0: 0403 3608 2ab4 00e9 b405 5cb6 0562 c700

0x00000d0: 0701 a700 102a b400 e9b4 055c b605 62b6

0x00000e0: 08bc 3a09 2bb6 08f2 b208 f6a6 002a bb09

0x00000f0: 0059 2ab6 02ff 2db6 068e 2bb6 08ee b204

0x0000100: eca6 0009 b209 05a7 0006 b209 08b7 090b

0x0000110: 3a0a a700 432b b609 0f3a 0bbb 0911 592a

0x0000120: b602 ff2d b606 8ebb 0913 5919 0bb4 039f

0x0000130: 190b b403 a219 0bb4 03a5 b709 142b b608

0x0000140: eeb2 04ec a600 09b2 0905 a700 06b2 0908

0x0000150: b709 173a 0a2a b400 f2b6 01f0 190a b901

0x0000160: f602 0015 0899 003e 190a b609 189a 0023

0x0000170: 2ab4 00e9 b405 5cb6 0562 c600 162a b400

0x0000180: e9b4 055c b605 62b6 08bc b208 fca5 0016

0x0000190: 2abb 091a 592d 2dc0 08fe b609 1db7 0920

0x00001a0: b601 8919 0ab6 0918 9a00 222a b400 e9b4

0x00001b0: 055c b605 62c6 0015 2ab4 00e9 b405 5cb6

0x00001c0: 0562 b608 bc19 09a5 0017 2abb 0922 592d

0x00001d0: b609 252d b609 2904 b709 2cb6 0189 190a

0x00001e0: b609 1899 0004 b12b b608 f2b2 08f6 a600

0x00001f0: 362b b608 ee3a 082a b400 e92d 1908 b609

0x0000200: 3057 1907 b606 0e9a 001a 1907 b609 3302

0x0000210: a300 112a b400 e92a b400 e9b4 0937 b609

0x0000220: 3ba7 00e8 2bb6 08f2 b208 f9a6 004c 2bb6

0x0000230: 08ee 3a08 2ab4 00e9 2d2b b609 0f19 08b8

0x0000240: 0941 c600 04b1 2d2a b400 e92b b609 0f19

0x0000250: 08b6 0945 5719 07b6 060e 9a00 1a19 07b6

0x0000260: 0933 02a3 0011 2ab4 00e9 2ab4 00e9 b409

0x0000270: 37b6 093b a700 952b b608 f2b2 0948 a600

0x0000280: 8b2d c109 4a9a 0023 2dc1 094c 9a00 1c2d

0x0000290: c109 4e9a 0015 2d2a b400 e9a6 0047 2ab4

0x00002a0: 00e9 b604 e69a 003d 2abb 0137 5913 0950

0x00002b0: 03bd 0004 b701 3cb6 0140 2ab4 00df bb01

0x00002c0: ca59 b701 cb13 0952 b601 d52a b400 e9b6

0x00002d0: 012f b601 d513 0954 b601 d5b6 01da b609

0x00002e0: 57b1 2ab4 00e9 2db6 095a 1907 b606 0e9a

0x00002f0: 001a 1907 b609 3302 a300 112a b400 e92a

0x0000300: b400 e9b4 0937 b609 3bb1

Stackmap Table:

same_frame(@23)

append_frame(@70,Object[#737],Object[#328])

append_frame(@106,Integer,Double)

same_locals_1_stack_item_frame(@137,Object[#235])

full_frame(@141,{Object[#2],Object[#91],Object[#737],Object[#328],Integer,Double},{Object[#235],Object[#1256]})

append_frame(@166,Object[#1446])

same_frame(@193)

same_locals_1_stack_item_frame(@194,Integer)

append_frame(@213,Integer)

same_locals_1_stack_item_frame(@226,Object[#2403])

full_frame(@266,{Object[#2],Object[#91],Object[#737],Object[#328],Integer,Double,Object[#1446],Integer,Object[#2403]},{Uninitialized[#238],Uninitialized[#238],Object[#252],Object[#2405]})

full_frame(@269,{Object[#2],Object[#91],Object[#737],Object[#328],Integer,Double,Object[#1446],Integer,Object[#2403]},{Uninitialized[#238],Uninitialized[#238],Object[#252],Object[#2405],Object[#2306]})

same_frame(@277)

full_frame(@333,{Object[#2],Object[#91],Object[#737],Object[#328],Integer,Double,Object[#1446],Integer,Object[#2403],Top,Object[#924]},{Uninitialized[#283],Uninitialized[#283],Object[#252],Object[#2405],Object[#2323]})

full_frame(@336,{Object[#2],Object[#91],Object[#737],Object[#328],Integer,Double,Object[#1446],Integer,Object[#2403],Top,Object[#924]},{Uninitialized[#283],Uninitialized[#283],Object[#252],Object[#2405],Object[#2323],Object[#2306]})

full_frame(@341,{Object[#2],Object[#91],Object[#737],Object[#328],Integer,Double,Object[#1446],Integer,Object[#2403],Object[#4]},{})

same_frame(@400)

same_frame(@419)

same_frame(@458)

same_frame(@478)

chop_frame(@487,3)

append_frame(@545,Object[#1256])

chop_frame(@548,1)

append_frame(@582,Object[#1256])

same_frame(@628)

chop_frame(@631,1)

same_frame(@680)

same_frame(@738)

chop_frame(@777,3)

[sciwhiz12]

Are you using bukkit/spigot? I see no mention of Forge, so...