I'm using an aternos server to play with this mod, i was building a gravel generator, and when it was time for the cobblestone to transform in gravel, the server just crashed, i left the machine on so i can't join my server anymore, any of my friends can't join now. (By the way i'm not 100% sure that the crushing wheel is the problem but, i think it has something to do with it)
Hopefully i recorded from start to end what i built, just saying in case that is needed.
In the console all i can find since i rejoined to the server is this:

[23:09:19] [Netty Epoll Server IO #4/ERROR] [minecraft/ArgumentTypes]: Could not serialize net.minecraftforge.server.command.ModIdArgument@1d4fef6d (class net.minecraftforge.server.command.ModIdArgument) - will not be sent to client! [23:09:19] [Netty Epoll Server IO #4/ERROR] [minecraft/ArgumentTypes]: Could not serialize net.minecraftforge.server.command.EnumArgument@8f1a909 (class net.minecraftforge.server.command.EnumArgument) - will not be sent to client! [23:09:20] [Server thread/ERROR] [minecraft/MinecraftServer]: Encountered an unexpected exception net.minecraft.crash.ReportedException: Ticking entity at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:833) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:324) ~[?:?] {re:classloading,pl:accesstransformer:B} at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:764) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:622) [?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222] {} Caused by: java.lang.ClassCastException: com.simibubi.create.modules.contraptions.relays.belt.BeltTileEntity cannot be cast to com.simibubi.create.modules.contraptions.receivers.CrushingWheelControllerTileEntity at com.simibubi.create.modules.contraptions.receivers.CrushingWheelControllerBlock.func_176216_a(CrushingWheelControllerBlock.java:69) ~[?:mc1.14.4_v0.1.1] {re:classloading} at net.minecraft.entity.Entity.func_213315_a(Entity.java:533) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} at net.minecraft.entity.item.ExperienceOrbEntity.func_70071_h_(ExperienceOrbEntity.java:114) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} at net.minecraft.world.server.ServerWorld.func_217479_a(ServerWorld.java:587) ~[?:?] {re:classloading,pl:runtimedistcleaner:A} at net.minecraft.world.World.func_217390_a(World.java:684) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} at net.minecraft.world.server.ServerWorld.func_72835_b(ServerWorld.java:394) ~[?:?] {re:classloading,pl:runtimedistcleaner:A} at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:829) ~[?:?] {re:classloading,pl:accesstransformer:B,pl:runtimedistcleaner:A} ... 4 more [23:09:20] [Server thread/ERROR] [minecraft/MinecraftServer]: This crash report has been saved to: /aternos/server/./crash-reports/crash-2019-10-16_23.09.20-server.txt [23:09:20] [Server thread/INFO] [minecraft/MinecraftServer]: Stopping server [23:09:20] [Server thread/INFO] [minecraft/MinecraftServer]: Saving players [23:09:20] [Server thread/INFO] [minecraft/ServerPlayNetHandler]: Gann4Life lost connection: Server closed [23:09:20] [Server thread/INFO] [minecraft/DedicatedServer]: Gann4Life left the game

Now i've found some code that's similar to that one...

[16Oct2019 23:09:19.201] [Server thread/INFO] [net.minecraft.server.dedicated.DedicatedServer/]: Gann4Life joined the game 63 | [16Oct2019 23:09:19.246] [Netty Epoll Server IO #4/ERROR] [net.minecraft.command.arguments.ArgumentTypes/]: Could not serialize net.minecraftforge.server.command.ModIdArgument@1d4fef6d (class net.minecraftforge.server.command.ModIdArgument) - will not be sent to client! 64 | [16Oct2019 23:09:19.249] [Netty Epoll Server IO #4/ERROR] [net.minecraft.command.arguments.ArgumentTypes/]: Could not serialize net.minecraftforge.server.command.EnumArgument@8f1a909 (class net.minecraftforge.server.command.EnumArgument) - will not be sent to client! 65 | [16Oct2019 23:09:20.556] [Server thread/ERROR] [net.minecraft.server.MinecraftServer/]: Encountered an unexpected exception 66 | net.minecraft.crash.ReportedException: Ticking entity 67 | at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:833) ~[?:?] 68 | at net.minecraft.server.dedicated.DedicatedServer.func_71190_q(DedicatedServer.java:324) ~[?:?] 69 | at net.minecraft.server.MinecraftServer.func_71217_p(MinecraftServer.java:764) ~[?:?] 70 | at net.minecraft.server.MinecraftServer.run(MinecraftServer.java:622) [?:?] 71 | at java.lang.Thread.run(Thread.java:748) [?:1.8.0_222] 72 | Caused by: java.lang.ClassCastException: com.simibubi.create.modules.contraptions.relays.belt.BeltTileEntity cannot be cast to com.simibubi.create.modules.contraptions.receivers.CrushingWheelControllerTileEntity 73 | at com.simibubi.create.modules.contraptions.receivers.CrushingWheelControllerBlock.func_176216_a(CrushingWheelControllerBlock.java:69) ~[?:mc1.14.4_v0.1.1] 74 | at net.minecraft.entity.Entity.func_213315_a(Entity.java:533) ~[?:?] 75 | at net.minecraft.entity.item.ExperienceOrbEntity.func_70071_h_(ExperienceOrbEntity.java:114) ~[?:?] 76 | at net.minecraft.world.server.ServerWorld.func_217479_a(ServerWorld.java:587) ~[?:?] 77 | at net.minecraft.world.World.func_217390_a(World.java:684) ~[?:?] 78 | at net.minecraft.world.server.ServerWorld.func_72835_b(ServerWorld.java:394) ~[?:?] 79 | at net.minecraft.server.MinecraftServer.func_71190_q(MinecraftServer.java:829) ~[?:?] 80 | ... 4 more 81 | [16Oct2019 23:09:20.602] [Server thread/ERROR] [net.minecraft.server.MinecraftServer/]: This crash report has been saved to: /aternos/server/./crash-reports/crash-2019-10-16_23.09.20-server.txt 82 | [16Oct2019 23:09:20.603] [Server thread/INFO] [net.minecraft.server.MinecraftServer/]: Stopping server

I just wanted to share this error (or maybe my mistake while building), but if any help could be provided, i will be thankful for that.

Thanks for reporting, for now you might be able to recover by

• navigating to the saves/[world name]/serverconfig folder
• open create-server.toml and look for [damageControl]
• set the value of freezeCrushing to true and restart your server.

If you get a chance to revisit/recreate your setup, sharing a screenshot of it would help immensely.
From what I can see in the log, it seems that a belt was placed in the space where the crushing wheels would've had their active area.

Should be fixed in 0.1.1a, feel free to re-open if the issue persists.