Forge version doesn't matter, its calling a client side only class on a server
cpw.mods.fml.common.LoaderException: java.lang.NoClassDefFoundError: net/minecraft/client/gui/GuiScreen
at cpw.mods.fml.common.LoadController.transition(LoadController.java:163)
at cpw.mods.fml.common.Loader.preinitializeMods(Loader.java:559)
at cpw.mods.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:88)
at cpw.mods.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:314)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:117)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:387)
at net.minecraft.server.MinecraftServer$2.run(MinecraftServer.java:685)
Caused by: java.lang.NoClassDefFoundError: net/minecraft/client/gui/GuiScreen
at drethic.questbook.item.QBItems.<clinit>(QBItems.java:7)
at drethic.questbook.proxy.CommonProxy.preInit(CommonProxy.java:12)
at drethic.questbook.proxy.ServerProxy.preInit(ServerProxy.java:11)
at drethic.questbook.QuestBook.preInit(QuestBook.java:28)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at cpw.mods.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:532)
at sun.reflect.GeneratedMethodAccessor3.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
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:212)
at cpw.mods.fml.common.LoadController.propogateStateMessage(LoadController.java:190)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
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:119)
at cpw.mods.fml.common.Loader.preinitializeMods(Loader.java:556)
... 5 more
Forge version doesn't matter, its calling a client side only class on a server