Versions:
-Minecraft Forge: 1.12.2 (14.23.5.2847)
-Industrial Renewal: 0.14.2

What happens:

Crash on start

What should happen:

Server start and mod active

Logs (if necessary):

---- Minecraft Crash Report ----
// Shall we play a game?

Time: 1/20/20 3:49 PM
Description: Exception in server tick loop

net.minecraftforge.fml.common.LoaderExceptionModCrash: Caught exception from Industrial Renewal (industrialrenewal)
Caused by: java.lang.NoClassDefFoundError: cassiokf/industrialrenewal/IRSoundHandler
at cassiokf.industrialrenewal.IndustrialRenewal.init(IndustrialRenewal.java:51)
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 net.minecraftforge.fml.common.FMLModContainer.handleModStateEvent(FMLModContainer.java:637)
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.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.sendEventToModContainer(LoadController.java:219)
at net.minecraftforge.fml.common.LoadController.propogateStateMessage(LoadController.java:197)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.google.common.eventbus.Subscriber.invokeSubscriberMethod(Subscriber.java:91)
at com.google.common.eventbus.Subscriber$SynchronizedSubscriber.invokeSubscriberMethod(Subscriber.java:150)
at com.google.common.eventbus.Subscriber$1.run(Subscriber.java:76)
at com.google.common.util.concurrent.MoreExecutors$DirectExecutor.execute(MoreExecutors.java:399)
at com.google.common.eventbus.Subscriber.dispatchEvent(Subscriber.java:71)
at com.google.common.eventbus.Dispatcher$PerThreadQueuedDispatcher.dispatch(Dispatcher.java:116)
at com.google.common.eventbus.EventBus.post(EventBus.java:217)
at net.minecraftforge.fml.common.LoadController.distributeStateMessage(LoadController.java:136)
at net.minecraftforge.fml.common.Loader.initializeMods(Loader.java:749)
at net.minecraftforge.fml.server.FMLServerHandler.finishServerLoading(FMLServerHandler.java:108)
at net.minecraftforge.fml.common.FMLCommonHandler.onServerStarted(FMLCommonHandler.java:338)
at net.minecraft.server.dedicated.DedicatedServer.func_71197_b(DedicatedServer.java:219)
at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:486)
at java.lang.Thread.run(Thread.java:748)
Caused by: java.lang.ClassNotFoundException: cassiokf.industrialrenewal.IRSoundHandler
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:191)
at java.lang.ClassLoader.loadClass(ClassLoader.java:424)
at java.lang.ClassLoader.loadClass(ClassLoader.java:357)
... 37 more
Caused by: net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerException: Exception in class transformer net.minecraftforge.fml.common.asm.transformers.SideTransformer@44f9779c from coremod FMLCorePlugin
at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:260)
at net.minecraft.launchwrapper.LaunchClassLoader.runTransformers(LaunchClassLoader.java:279)
at net.minecraft.launchwrapper.LaunchClassLoader.findClass(LaunchClassLoader.java:176)
... 39 more
Caused by: java.lang.RuntimeException: Attempted to load class cassiokf/industrialrenewal/IRSoundHandler for invalid side SERVER
at net.minecraftforge.fml.common.asm.transformers.SideTransformer.transform(SideTransformer.java:62)
at net.minecraftforge.fml.common.asm.ASMTransformerWrapper$TransformerWrapper.transform(ASMTransformerWrapper.java:256)
... 41 more

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

-- System Details --
Details:
Minecraft Version: 1.12.2
Operating System: Linux (amd64) version 4.4.0-164-generic
Java Version: 1.8.0_222, Oracle Corporation
Java VM Version: OpenJDK 64-Bit Server VM (mixed mode), Oracle Corporation
Memory: 490958640 bytes (468 MB) / 1001914368 bytes (955 MB) up to 1398276096 bytes (1333 MB)
JVM Flags: 3 total; -XX:MaxMetaspaceSize=200M -Xmx1500M -Xms750M
IntCache: cache: 0, tcache: 0, allocated: 0, tallocated: 0
FML: MCP 9.42 Powered by Forge 14.23.5.2847 5 mods loaded, 5 mods active
States: 'U' = Unloaded 'L' = Loaded 'C' = Constructed 'H' = Pre-initialized 'I' = Initialized 'J' = Post-initialized 'A' = Available 'D' = Disabled 'E' = Errored

| State | ID                | Version      | Source                              | Signature |
|:----- |:----------------- |:------------ |:----------------------------------- |:--------- |
| LCHI  | minecraft         | 1.12.2       | minecraft.jar                       | None      |
| LCHI  | mcp               | 9.42         | minecraft.jar                       | None      |
| LCHI  | FML               | 8.0.99.99    | forge.jar                           | None      |
| LCHI  | forge             | 14.23.5.2847 | forge.jar                           | None      |
| LCHE  | industrialrenewal | 0.14.2       | IndustrialRenewal_1.12.2-0.14.2.jar | None      |

Loaded coremods (and transformers): 
Profiler Position: N/A (disabled)
Is Modded: Definitely; Server brand changed to 'fml,forge'
Type: Dedicated Server (map_server.txt)

Additional Comments:

Works on singleplayer