Dear,

with the last version (copperhopper-0.5.0+1.20.1.jar), on server Fabric 1.20.1, i have a bug :
(no problem with copperhopper-0.4.0+1.20.1.jar, only 0.5.0)

Minecraft 1.20.1 with Fabric Loader 0.14.21, fabric-api-0.88.1+1.20.1.jar

[07:09:18] [main/INFO]: Loading Minecraft 1.20.1 with Fabric Loader 0.14.21
[07:09:18] [ForkJoinPool-1-worker-7/WARN]: Mod allstackable uses the version v2.0.0-1.20.1 which isn't compatible with Loader's extended semantic version format (Could not parse version number component 'v2'!), SemVer is recommended for reliably evaluating dependencies and prioritizing newer version
[07:09:18] [main/INFO]: Loading 155 mods:
- additionalstructures 4.2.0
- allstackable v2.0.0-1.20.1
- anvilrestoration 2.0
- architectury 9.1.12
- bakery 1.1.2
- balm-fabric 7.1.4
- betterconduitplacement 3.0
- betterdeserttemples 1.20-Fabric-3.0.2
-- org_reflections_reflections 0.10.2
- betterdungeons 1.20-Fabric-4.0.2
- betterfortresses 1.20-Fabric-2.0.3
- betterjungletemples 1.20-Fabric-2.0.2
- bettermineshafts 1.20-Fabric-4.0.3
- betteroceanmonuments 1.20-Fabric-3.0.2
- betterspawnercontrol 4.2
- betterstrongholds 1.20-Fabric-4.0.2
- betterwitchhuts 1.20-Fabric-3.0.2
- biggerspongeabsorptionradius 3.1
- blossom 1.0.7
- bookshelf 20.0.4
- bottleyourxp 3.1
- candlelight 1.2.4
- chunkloaders 1.2.7+a
- chunksending 1.20.1-2.6
- cloth-config 11.1.106
-- cloth-basic-math 0.6.1
- coinsje 12.0.1
- collective 6.66
- copper_pipe 1.13.6
- copperhopper 0.5.0+1.20.1
- cropped 1.0.1
- cupboard 1.20.1-2.0
- despawningeggshatch 4.1
- dismountentity 3.0
- doapi 1.2.7
|-- blue_endless_jankson 1.2.1
-- terraform-wood-api-v1 7.0.1
- doubledoors 5.0
- easyelytratakeoff 4.0
- elytraslot 6.3.0+1.20.1
- extendedbonemeal 3.0
- fabric-api 0.88.1+1.20.1
|-- fabric-api-base 0.4.30+7abfd51577
|-- fabric-api-lookup-api-v1 1.6.35+4d8536c977
|-- fabric-biome-api-v1 13.0.10+b3afc78b77
|-- fabric-block-api-v1 1.0.10+92a0d36777
|-- fabric-block-view-api-v2 1.0.0+92a0d36777
|-- fabric-blockrenderlayer-v1 1.1.40+b3afc78b77
|-- fabric-client-tags-api-v1 1.1.1+97bb207577
|-- fabric-command-api-v1 1.2.33+f71b366f77
|-- fabric-command-api-v2 2.2.12+b3afc78b77
|-- fabric-commands-v0 0.2.50+df3654b377
|-- fabric-containers-v0 0.1.63+df3654b377
|-- fabric-content-registries-v0 4.0.9+b3afc78b77
|-- fabric-convention-tags-v1 1.5.4+a1a980da77
|-- fabric-crash-report-info-v1 0.2.18+aeb40ebe77
|-- fabric-data-generation-api-v1 12.2.2+1e61dba177
|-- fabric-dimensions-v1 2.1.53+8536527b77
|-- fabric-entity-events-v1 1.5.22+b3afc78b77
|-- fabric-events-interaction-v0 0.6.1+e91849a877
|-- fabric-events-lifecycle-v0 0.2.62+df3654b377
|-- fabric-game-rule-api-v1 1.0.38+b04edc7a77
|-- fabric-item-api-v1 2.1.27+b3afc78b77
|-- fabric-item-group-api-v1 4.0.10+23d9108177
|-- fabric-key-binding-api-v1 1.0.36+fb8d95da77
|-- fabric-keybindings-v0 0.2.34+df3654b377
|-- fabric-lifecycle-events-v1 2.2.21+b3afc78b77
|-- fabric-loot-api-v2 1.1.39+b3afc78b77
|-- fabric-loot-tables-v1 1.1.43+9e7660c677
|-- fabric-message-api-v1 5.1.7+3265161977
|-- fabric-mining-level-api-v1 2.1.49+b3afc78b77
|-- fabric-model-loading-api-v1 1.0.2+709a987177
|-- fabric-models-v0 0.4.1+9386d8a777
|-- fabric-networking-api-v1 1.3.10+eeb8eb3677
|-- fabric-networking-v0 0.3.50+df3654b377
|-- fabric-object-builder-api-v1 11.1.1+6beca84877
|-- fabric-particles-v1 1.1.1+201a23a077
|-- fabric-recipe-api-v1 1.0.20+b3afc78b77
|-- fabric-registry-sync-v0 2.3.2+4df89eb277
|-- fabric-renderer-api-v1 3.1.3+92a0d36777
|-- fabric-renderer-indigo 1.4.3+6bdb2ed077
|-- fabric-renderer-registries-v1 3.2.45+df3654b377
|-- fabric-rendering-data-attachment-v1 0.3.36+92a0d36777
|-- fabric-rendering-fluids-v1 3.0.27+b3afc78b77
|-- fabric-rendering-v0 1.1.48+df3654b377
|-- fabric-rendering-v1 3.0.7+b3afc78b77
|-- fabric-resource-conditions-api-v1 2.3.5+ea08f9d877
|-- fabric-resource-loader-v0 0.11.9+132c48c177
|-- fabric-screen-api-v1 2.0.7+b3afc78b77
|-- fabric-screen-handler-api-v1 1.3.29+b3afc78b77
|-- fabric-sound-api-v1 1.0.12+b3afc78b77
|-- fabric-transfer-api-v1 3.3.1+195226a777
-- fabric-transitive-access-wideners-v1 4.3.0+6c31357e77
- fabricloader 0.14.21
- fallingtree 4.3.0
- ferritecore 6.0.0
- fixedanvilrepaircost 3.1
- forcecrawl 1.0.2
- forgeconfigapiport 8.0.0
- furnacerecycle 2.0
- grindenchantments 3.1.2+1.20
-- codec-config-api 1.0.2+1.19.3
- healingcampfire 5.1
- hoetweaks 3.2
- huskspawn 3.3
- imst 2.1.0
- imst_n 1.0.0
- inventorysorter 1.9.0-1.20
-- kyrptconfig 1.5.6-1.20
- jade 11.5.1
- java 17
- jei 15.2.0.27
- justmobheads 7.3
- keepmysoiltilled 2.0
- kleeslabs 15.0.0
- krypton 0.2.3
-- com_velocitypowered_velocity-native 3.2.0-SNAPSHOT
- lazydfu 0.1.3
- lithium 0.11.2
- magnumtorch 8.0.0
- microcutting 1.20-rc1-1.5.0
- midnightlib 1.4.1
- minecraft 1.20.1
- mixin-conflict-helper 1.2.0
- mooshroomtweaks 3.2
- naturallychargedcreepers 3.2
- neruina 1.2.3
|-- com_github_llamalad7_mixinextras 0.2.0-rc.4
-- mixinsquared 0.0.2
- netherportalfix 13.0.0
- notenoughcrashes 4.4.6+1.20.1
- petnames 3.0
- puzzleslib 8.0.24
- replantingcrops 5.1
- repurposed_structures 7.1.6+1.20.1-fabric
- scaffoldingdropsnearby 3.0
- separatedleaves 2.2.0
- skeletonhorsespawn 3.6
- smallernetherportals 3.4
- smart-villagers-follow-emeralds 1.0.0
- smoothchunk 1.20.1-3.2
- softerhaybales 3.0
- spark 1.10.53
-- fabric-permissions-api-v0 0.1-SNAPSHOT
- stackrefill 4.0
- starlight 1.1.2+fabric.dbc156f
- structureessentials 1.20.1-3.0
- supermartijn642configlib 1.1.8
- supermartijn642corelib 1.1.12+d
- tntbreaksbedrock 3.0
- toofast 1.2.0
- trade_cycling 1.20.1-1.0.7
|-- fabric-key-binding-api-v1 1.0.36+fb8d95da82
-- fabric-screen-api-v1 2.0.6+b3afc78b82
- trinkets 3.7.1
- universalenchants 8.0.0
|-- cardinal-components-base 5.2.1
|-- cardinal-components-entity 5.2.1
-- extensibleenums 7.0.1
- vanityslots 1.2.9
- villagernames 5.2
- villagersplus 2.1
- vinery 1.4.4
- weakerspiderwebs 3.2
- wooltweaks 3.1
- yungsapi 1.20-Fabric-4.0.1
-- org_javassist_javassist 3.29.2-GA
- yungsbridges 1.20-Fabric-4.0.2
- yungsextras 1.20-Fabric-4.0.2
- zombiehorsespawn 4.6
[07:09:19] [main/INFO]: SpongePowered MIXIN Subsystem Version=0.8.5 Source=file:/home/container/libraries/net/fabricmc/sponge-mixin/0.12.5+mixin.0.8.5/sponge-mixin-0.12.5+mixin.0.8.5.jar Service=Knot/Fabric Env=SERVER
[07:09:19] [main/INFO]: Compatibility level set to JAVA_17
[07:09:21] [main/WARN]: Error loading class: net/coderbot/iris/Iris (java.lang.ClassNotFoundException: net/coderbot/iris/Iris)
[07:09:21] [main/WARN]: @mixin target net.coderbot.iris.Iris was not found notenoughcrashes.fabric.mixins.json:iris.SilentNEC from mod notenoughcrashes
[07:09:21] [main/INFO]: Loaded config for: structureessentials.json
[07:09:21] [main/INFO]: Initializing MixinExtras via com.llamalad7.mixinextras.service.MixinExtrasServiceImpl(version=0.2.0-rc.4).
[07:09:39] [main/INFO]: [All Stackable] Start loading!
[07:09:39] [main/INFO]: [All Stackable] Command registered.
[07:09:40] [main/ERROR]: No data fixer registered for bakery:wandering_baker
[07:09:41] [main/INFO]: Registering C2S receiver with id candlelight:typewriter_sync
[07:09:41] [main/INFO]: Registering C2S receiver with id candlelight:sign_note
[07:09:41] [main/INFO]: Loaded config for: chunksending.json
[07:09:41] [main/INFO]: chunksending mod initialized
[07:09:41] [main/INFO]: Loading Collective version 6.66.
[07:09:42] [main/INFO]: Compression will use libdeflate (Linux x86_64), encryption will use OpenSSL 1.1.x (Linux x86_64)
[07:09:42] [main/INFO]: Constructing common components for magnumtorch:main
[07:09:43] [main/INFO]: Initializing Neruina
[07:09:43] [main/INFO]: Constructing common components for puzzleslib:main
[07:09:43] [main/INFO]: structureessentials mod initialized
[07:09:43] [main/INFO]: Registered JSON trade offer adapter.
[07:09:43] [main/ERROR]: Failed to start the minecraft server
java.lang.RuntimeException: Could not execute entrypoint stage 'main' due to errors, provided by 'copperhopper'!
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.lambda$invoke0$0(EntrypointUtils.java:51) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.util.ExceptionUtil.gatherExceptions(ExceptionUtil.java:33) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke0(EntrypointUtils.java:49) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke(EntrypointUtils.java:35) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.game.minecraft.Hooks.startServer(Hooks.java:62) ~[fabric-loader-0.14.21.jar:?]
at net.minecraft.server.Main.main(Main.java:112) ~[server-intermediary.jar:?]
at net.fabricmc.loader.impl.game.minecraft.MinecraftGameProvider.launch(MinecraftGameProvider.java:468) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.launch.knot.Knot.launch(Knot.java:74) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotServer.main(KnotServer.java:23) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.launch.server.FabricServerLauncher.main(FabricServerLauncher.java:69) ~[fabric-loader-0.14.21.jar:?]
Caused by: java.lang.NoClassDefFoundError: net/minecraft/class_897
at net.pcal.copperhopper.CohoInitializer.onInitialize(CohoInitializer.java:70) ~[copperhopper-0.5.0+1.20.1.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke0(EntrypointUtils.java:47) ~[fabric-loader-0.14.21.jar:?]
... 7 more
Caused by: java.lang.ClassNotFoundException: net.minecraft.class_897
at jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:641) ~[?:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassDelegate.loadClass(KnotClassDelegate.java:226) ~[fabric-loader-0.14.21.jar:?]
at net.fabricmc.loader.impl.launch.knot.KnotClassLoader.loadClass(KnotClassLoader.java:112) ~[fabric-loader-0.14.21.jar:?]
at java.lang.ClassLoader.loadClass(ClassLoader.java:525) ~[?:?]
at net.pcal.copperhopper.CohoInitializer.onInitialize(CohoInitializer.java:70) ~[copperhopper-0.5.0+1.20.1.jar:?]
at net.fabricmc.loader.impl.entrypoint.EntrypointUtils.invoke0(EntrypointUtils.java:47) ~[fabric-loader-0.14.21.jar:?]
... 7 more

I have this error too. I'm running 1.20.1 with Quilt server 0.20.2. The mod works just fine clientside.

should be fixed in 0.5.1