As it's been working fine locally, how can it be completely broken?
Edit: Just tried running it on my server and it is indeed absolutely broken - would however like to know why so I can fix it =)
Edit2: Added log if it helps in any way.
[11:58:05] [main/INFO] [LaunchWrapper]: Loading tweak class name net.minecraftforge.fml.common.launcher.FMLServerTweaker
[11:58:05] [main/INFO] [LaunchWrapper]: Using primary tweak class name net.minecraftforge.fml.common.launcher.FMLServerTweaker
[11:58:05] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.common.launcher.FMLServerTweaker
[11:58:05] [main/INFO] [FML]: Forge Mod Loader version 14.23.3.2655 for Minecraft 1.12.2 loading
[11:58:05] [main/INFO] [FML]: Java is Java HotSpot(TM) 64-Bit Server VM, version 1.8.0_131, running on Windows 8.1:amd64:6.3, installed at C:\Program Files\Java\jre1.8.0_131
[11:58:06] [main/INFO] [LaunchWrapper]: Loading tweak class name net.minecraftforge.fml.common.launcher.FMLInjectionAndSortingTweaker
[11:58:06] [main/INFO] [LaunchWrapper]: Loading tweak class name net.minecraftforge.fml.common.launcher.FMLDeobfTweaker
[11:58:06] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.common.launcher.FMLInjectionAndSortingTweaker
[11:58:06] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.common.launcher.FMLInjectionAndSortingTweaker
[11:58:06] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.relauncher.CoreModManager$FMLPluginWrapper
[11:58:09] [main/INFO] [FML]: Found valid fingerprint for Minecraft Forge. Certificate fingerprint e3c3d50c7c986df74c645c0ac54639741c90a557
[11:58:09] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.relauncher.CoreModManager$FMLPluginWrapper
[11:58:09] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.common.launcher.FMLDeobfTweaker
[11:58:11] [main/INFO] [LaunchWrapper]: Loading tweak class name net.minecraftforge.fml.common.launcher.TerminalTweaker
[11:58:11] [main/INFO] [LaunchWrapper]: Calling tweak class net.minecraftforge.fml.common.launcher.TerminalTweaker
[11:58:11] [main/INFO] [LaunchWrapper]: Launching wrapped minecraft {net.minecraft.server.MinecraftServer}
[11:58:18] [Server thread/INFO] [net.minecraft.server.dedicated.DedicatedServer]: Starting minecraft server version 1.12.2
[11:58:18] [Server thread/INFO] [FML]: MinecraftForge v14.23.3.2655 Initialized
[11:58:18] [Server thread/INFO] [FML]: Starts to replace vanilla recipe ingredients with ore ingredients.
[11:58:18] [Server thread/INFO] [FML]: Replaced 1036 ore ingredients
[11:58:19] [Server thread/INFO] [FML]: Found 0 mods from the command line. Injecting into mod discoverer
[11:58:19] [Server thread/INFO] [FML]: Searching C:\Users\Frederik\Desktop\Forge server\mods for mods
[11:58:19] [Server thread/INFO] [FML]: Forge Mod Loader has identified 5 mods to load
[11:58:19] [Server thread/WARN] [FML]: Missing English translation for FML: assets/fml/lang/en_us.lang
[11:58:20] [Server thread/INFO] [FML]: Attempting connection with missing mods [minecraft, mcp, FML, forge, um] at CLIENT
[11:58:20] [Server thread/INFO] [FML]: Attempting connection with missing mods [minecraft, mcp, FML, forge, um] at SERVER
[11:58:21] [Server thread/INFO] [FML]: Processing ObjectHolder annotations
[11:58:21] [Server thread/INFO] [FML]: Found 1168 ObjectHolder annotations
[11:58:21] [Server thread/INFO] [FML]: Identifying ItemStackHolder annotations
[11:58:21] [Server thread/INFO] [FML]: Found 0 ItemStackHolder annotations
[11:58:21] [Server thread/INFO] [FML]: Configured a dormant chunk cache size of 0
[11:58:21] [Forge Version Check/INFO] [forge.VersionCheck]: [forge] Starting version check at http://files.minecraftforge.net/maven/net/minecraftforge/forge/promotions_slim.json
[11:58:21] [Server thread/INFO] [FML]: Applying holder lookups
[11:58:22] [Server thread/INFO] [FML]: Holder lookups applied
[11:58:22] [Server thread/ERROR] [FML]: Exception caught during firing event net.minecraftforge.event.RegistryEvent$Register@67fc26f6:
java.lang.NoClassDefFoundError: com/mta/utzonmod/client/gui/signInputGui
at com.mta.utzonmod.items.SchematicSign.<init>(SchematicSign.java:21) ~[SchematicSign.class:?]
at com.mta.utzonmod.init.ModItems.<clinit>(ModItems.java:15) ~[ModItems.class:?]
at com.mta.utzonmod.util.handlers.RegistryHandler.onItemRegister(RegistryHandler.java:16) ~[RegistryHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_5_RegistryHandler_onItemRegister_Register.invoke(.dynamic) ~[?:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus$1.invoke(EventBus.java:143) ~[EventBus$1.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:179) [EventBus.class:?]
at net.minecraftforge.registries.GameData.fireRegistryEvents(GameData.java:739) [GameData.class:?]
at net.minecraftforge.fml.common.Loader.preinitializeMods(Loader.java:604) [Loader.class:?]
at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98) [FMLServerHandler.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:332) [FMLCommonHandler.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125) [nz.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_131]
Caused by: java.lang.ClassNotFoundException: com.mta.utzonmod.client.gui.signInputGui
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
... 14 more
Caused by: net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerException: Exception in class transformer net.minecraftforge.fml.common.asm.transformers.SideTransformer@28a2a3e7 from coremod FMLCorePlugin
at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:262) ~[forge-1.12.2-14.23.3.2655-universal.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279) ~[launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
... 14 more
Caused by: java.lang.RuntimeException: Attempted to load class com/mta/utzonmod/client/gui/signInputGui for invalid side SERVER
at net.minecraftforge.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:62) ~[forge-1.12.2-14.23.3.2655-universal.jar:?]
at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:258) ~[forge-1.12.2-14.23.3.2655-universal.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279) ~[launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
... 14 more
[11:58:22] [Server thread/ERROR] [FML]: Index: 2 Listeners:
[11:58:22] [Server thread/ERROR] [FML]: 0: NORMAL
[11:58:22] [Server thread/ERROR] [FML]: 1: net.minecraftforge.fml.common.eventhandler.EventBus$1@26df43d6
[11:58:22] [Server thread/ERROR] [FML]: 2: net.minecraftforge.fml.common.eventhandler.EventBus$1@56679711
[11:58:22] [Server thread/ERROR] [net.minecraft.server.MinecraftServer]: Encountered an unexpected exception
java.lang.NoClassDefFoundError: com/mta/utzonmod/client/gui/signInputGui
at com.mta.utzonmod.items.SchematicSign.<init>(SchematicSign.java:21) ~[SchematicSign.class:?]
at com.mta.utzonmod.init.ModItems.<clinit>(ModItems.java:15) ~[ModItems.class:?]
at com.mta.utzonmod.util.handlers.RegistryHandler.onItemRegister(RegistryHandler.java:16) ~[RegistryHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler_5_RegistryHandler_onItemRegister_Register.invoke(.dynamic) ~[?:?]
at net.minecraftforge.fml.common.eventhandler.ASMEventHandler.invoke(ASMEventHandler.java:90) ~[ASMEventHandler.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus$1.invoke(EventBus.java:143) ~[EventBus$1.class:?]
at net.minecraftforge.fml.common.eventhandler.EventBus.post(EventBus.java:179) ~[EventBus.class:?]
at net.minecraftforge.registries.GameData.fireRegistryEvents(GameData.java:739) ~[GameData.class:?]
at net.minecraftforge.fml.common.Loader.preinitializeMods(Loader.java:604) ~[Loader.class:?]
at net.minecraftforge.fml.server.FMLServerHandler.beginServerLoading(FMLServerHandler.java:98) ~[FMLServerHandler.class:?]
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStart(FMLCommonHandler.java:332) ~[FMLCommonHandler.class:?]
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:125) ~[nz.class:?]
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:484) [MinecraftServer.class:?]
at java.lang.Thread.run(Unknown Source) [?:1.8.0_131]
Caused by: java.lang.ClassNotFoundException: com.mta.utzonmod.client.gui.signInputGui
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
... 14 more
Caused by: net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerException: Exception in class transformer net.minecraftforge.fml.common.asm.transformers.SideTransformer@28a2a3e7 from coremod FMLCorePlugin
at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:262) ~[forge-1.12.2-14.23.3.2655-universal.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279) ~[launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
... 14 more
Caused by: java.lang.RuntimeException: Attempted to load class com/mta/utzonmod/client/gui/signInputGui for invalid side SERVER
at net.minecraftforge.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:62) ~[forge-1.12.2-14.23.3.2655-universal.jar:?]
at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:258) ~[forge-1.12.2-14.23.3.2655-universal.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279) ~[launchwrapper-1.12.jar:?]
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176) ~[launchwrapper-1.12.jar:?]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
at java.lang.ClassLoader.loadClass(Unknown Source) ~[?:1.8.0_131]
... 14 more
[11:58:22] [Forge Version Check/INFO] [forge.VersionCheck]: [forge] Found status: UP_TO_DATE Target: null
[11:58:22] [Server thread/ERROR] [net.minecraft.server.MinecraftServer]: This crash report has been saved to: C:\Users\Frederik\Desktop\Forge server\.\crash-reports\crash-2018-05-03_11.58.22-server.txt
[11:58:22] [Server thread/INFO] [net.minecraft.server.MinecraftServer]: Stopping server
[11:58:22] [Server thread/INFO] [net.minecraft.server.MinecraftServer]: Saving worlds
[11:58:22] [Server thread/WARN] [FML]: Can't revert to frozen GameData state without freezing first.
[11:58:22] [Server thread/INFO] [FML]: The state engine was in incorrect state INITIALIZATION and forced into state SERVER_STOPPED. Errors may have been discarded.
[11:58:22] [Server Shutdown Thread/INFO] [net.minecraft.server.MinecraftServer]: Stopping server
[11:58:22] [Server Shutdown Thread/INFO] [net.minecraft.server.MinecraftServer]: Saving worlds