{:10_512:}昨天还好好的今天就这样了求解决方法

请发错误报告

---- Minecraft Crash Report ----
// Everything's going to plan. No, really, that was supposed to happen.

Time: 15-7-16 下午3:11
Description: Exception in server tick loop

java.lang.NoClassDefFoundError: net/minecraft/client/multiplayer/WorldClient
        at java.lang.Class.forName0(Native Method)
        at java.lang.Class.forName(Unknown Source)
        at cpw.mods.fml.common.ProxyInjector.inject(ProxyInjector.java:59)
        at cpw.mods.fml.common.FMLModContainer.constructMod(FMLModContainer.java:492)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
        at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
        at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
        at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
        at com.google.common.eventbus.EventBus.post(EventBus.java:275)
        at cpw.mods.fml.common.LoadController.sendEventToModContainer(LoadController.java:208)
        at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:187)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
        at java.lang.reflect.Method.invoke(Unknown Source)
        at com.google.common.eventbus.EventSubscriber.handleEvent(EventSubscriber.java:74)
        at com.google.common.eventbus.SynchronizedEventSubscriber.handleEvent(SynchronizedEventSubscriber.java:47)
        at com.google.common.eventbus.EventBus.dispatch(EventBus.java:322)
        at com.google.common.eventbus.EventBus.dispatchQueuedEvents(EventBus.java:304)
        at com.google.common.eventbus.EventBus.post(EventBus.java:275)
        at cpw.mods.fml.common.LoadController.distributeStateMessage(LoadController.java:118)
        at cpw.mods.fml.common.Loader.loadMods(Loader.java:492)
        at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:87)
        at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:319)
        at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:170)
        at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:620)
        at java.lang.Thread.run(Unknown Source)
Caused by: java.lang.ClassNotFoundException: net.minecraft.client.multiplayer.WorldClient
        at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        at java.lang.ClassLoader.loadClass(Unknown Source)
        ... 31 more
Caused by: java.lang.RuntimeException: Attempted to load class bjf for invalid side SERVER
        at cpw.mods.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:51)
        at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279)
        at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176)
        ... 33 more


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

-- System Details --
Details:
        Minecraft Version: 1.7.10
        Operating System: Windows 7 (x86) version 6.1
        Java Version: 1.7.0_79, Oracle Corporation
        Java VM Version: Java HotSpot(TM) Client VM (mixed mode), Oracle Corporation
        Memory: 888962856 bytes (847 MB) / 1037959168 bytes (989 MB) up to 1037959168 bytes (989 MB)
        JVM Flags: 2 total; -Xmx1024M -Xms1024M
        AABB Pool Size: 0 (0 bytes; 0 MB) allocated, 0 (0 bytes; 0 MB) used
        IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
        FML: ~~ERROR~~ NullPointerException: null
        Profiler Position: N/A (disabled)
        Is Modded: Definitely; Server brand changed to 'cauldron,craftbukkit,mcpc,fml,forge'
        Type: Dedicated Server (map_server.txt)

不完整吧

就这么多的。。

经常发生吗？

今天才发生

libraries文件缺少了东西

怎么修复

应该问题不大吧