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I am playing 1.8.7 Minecraft, no mods, no resource packs. I go into the Minecraft launcher, click player, and the Mojang Screen comes up as usual. The the Title Screen. I click Multiplayer and Minecraft crashes. It doesn't let me report a crash to Mojang, it only allows me to open the report file. I tried going into Singleplayer and it works fine, but any time I click Multiplayer it crashes. The odd thing about this is Multiplayer was working yesterday, and I haven't downloaded anything or changed anything on my laptop since that night. I am not sure what happened or why it stopped working, but please help. Thank you.

This is the crash report:

---- Minecraft Crash Report ----
// But it works on my machine.

Time: 7/21/15 12:57 PM
Description: Updating screen events

java.lang.VerifyError: Bad type on operand stack
Exception Details:
Location:
bdf.<init>(Lats;Labv;Laup;Lbct;)V @27: invokespecial
Reason:
Type 'bdf' (current frame, stack[3]) is not assignable to 'ue'
Current Frame:
bci: @27
flags: { }
locals: { 'bdf', 'ats', 'abv', 'aup', 'bct' }
stack: { 'bdf', uninitialized 22, uninitialized 22, 'bdf' }
Bytecode:
0x0000000: 2a2b 2c2d 03b7 0023 2a14 0024 b500 272a
0x0000010: 1904 b500 292a bb00 2b59 2ab7 002e b500
0x0000020: 30b1

at azh.b(SourceFile:63)
at axu.a(SourceFile:376)
at ave.a(SourceFile:818)
at aya.a(SourceFile:218)
at axu.a(SourceFile:350)
at aya.a(SourceFile:468)
at axu.k(SourceFile:413)
at axu.p(SourceFile:390)
at ave.s(SourceFile:1497)
at ave.av(SourceFile:888)
at ave.a(SourceFile:325)
at net.minecraft.client.main.Main.main(SourceFile:124)

A detailed walkthrough of the error, its code path and all known details is as follows:
---------------------------------------------------------------------------------------

-- Head --
Stacktrace:
at azh.b(SourceFile:63)
at axu.a(SourceFile:376)
at ave.a(SourceFile:818)
at aya.a(SourceFile:218)
at axu.a(SourceFile:350)
at aya.a(SourceFile:468)
at axu.k(SourceFile:413)
at axu.p(SourceFile:390)

-- Affected screen --
Details:
Screen name: azh
Stacktrace:
at ave.s(SourceFile:1497)
at ave.av(SourceFile:888)
at ave.a(SourceFile:325)
at net.minecraft.client.main.Main.main(SourceFile:124)

-- System Details --
Details:
Minecraft Version: 1.8.7
Operating System: Windows 8.1 (amd64) version 6.3
CPU: 2x Intel(R) Pentium(R) CPU 2127U @ 1.90GHz
Java Version: 1.8.0_25, Oracle Corporation
Java VM Version: Java HotSpot(TM) 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 119565536 bytes (114 MB) / 216014848 bytes (206 MB) up to 1060372480 bytes (1011 MB)
JVM Flags: 6 total; -XX:HeapDumpPath=MojangTricksIntelDriversForPerformance_javaw.exe_minecraft.exe.heapdump -Xmx1G -XX:+UseConcMarkSweepGC -XX:+CMSIncrementalMode -XX:-UseAdaptiveSizePolicy -Xmn128M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
Launched Version: 1.8.7SPC
LWJGL: 2.9.4
OpenGL: Intel(R) HD Graphics GL version 4.0.0 - Build 10.18.10.3621, Intel
GL Caps: Using GL 1.3 multitexturing.
Using GL 1.3 texture combiners.
Using framebuffer objects because OpenGL 3.0 is supported and separate blending is supported.
Shaders are available because OpenGL 2.1 is supported.
VBOs are available because OpenGL 1.5 is supported.

Using VBOs: No
Is Modded: Very likely; Jar signature invalidated
Type: Client (map_client.txt)
Resource Packs: []
Current Language: English (US)
Profiler Position: N/A (disabled)

Its modded. It says Is Modded: Very likely; Jar signature invalidated

You might try to reinstall minecraft