| name | minecraft-client-to-server-pack |
| description | Use ServerPackCreator (Griefed) CLI to convert a Minecraft client modpack (CurseForge .zip or Modrinth .mrpack) into a runnable server pack. Java 21, Arch/WSL friendly. Outputs zip + flat directory with start.sh/.bat/.ps1 + server.properties. Use when user has a client modpack and needs a server-side jar/scripts. |
Minecraft client modpack → server pack
Convert a client modpack (the one a player launches) into a server pack (the one a server runs) using Griefed's ServerPackCreator (SPC).
When to use
- User says "把这个整合包做成服务端" / "generate server pack from this modpack" / "client 转 server"
- Has a modpack zip / extracted dir; wants a deployable server pack
When NOT to use
- User has a server pack already (zip with
start.sh, mods/, server.properties) → use official gaming/minecraft-modpack-server skill instead
- User wants to host on a public server with port-forwarding → official skill covers deployment
Prerequisites
| Item | Notes |
|---|
| Java 21 (JDK) | sudo pacman -S jdk21-openjdk (Arch) / apt install openjdk-21-jdk (Debian) |
| SPC jar | Download from https://github.com/Griefed/ServerPackCreator/releases (latest, e.g. ServerPackCreator-8.1.2.jar) — GUI download is more reliable than WSL curl/gh release (gh release asset URL has JWT expiry that breaks wget resume) |
| Modpack | CurseForge zip OR Modrinth .mrpack OR extracted dir |
Workflow (3 commands)
1. Unpack if needed
2. Generate config (interactive, but only on first run)
java -jar ~/spc/spc.jar -cgen ~/spc/work/modpack_src -config ~/ServerPackCreator/configs/<name>.conf
-cgen writes the conf but does NOT fill minecraftVersion / modLoader / modLoaderVersion from the modpack manifest — fill these manually:
- For Modrinth modpacks: read
modpack_src/modrinth.index.json → dependencies.minecraft, dependencies.forge/fabric/quilt
- For CurseForge modpacks: read
modpack_src/manifest.json → minecraft.modLoaders[].id, minecraft.version
Edit ~/ServerPackCreator/configs/<name>.conf → set the 3 fields.
3. ⚠️ The TWO traps: inclusions field AND modpackDir choice
Trap 1 — modpackDir wrong → wrong code path:
modpackDir points to | SPC sees | Result |
|---|
PCL instance dir (.../versions/<name>/) | mods/ + config/ + manifest at top | Treats as installed modpack → all jars, full ~315 mod server pack |
Zip-extracted dir (.../work/modpack_src/) | overrides/ + manifest at top | Treats as modrinth staging → only downloads modrinth manifest mods → ~38 mod server pack (broken) |
Use the launcher instance dir, not the zip-extracted dir. On WSL: modpackDir = "/mnt/e/.minecraft/versions/Chapter of Yuusha 3". On Windows GUI: modpackDir = "E:\.minecraft\versions\Chapter of Yuusha 3".
Trap 2 — inclusions empty → empty server pack:
-cgen produces inclusions = []. Without filling this, SPC exits with:
ERROR: No directories or files specified for copying. This would result in an empty serverpack.
Format (InclusionSpecification: source/destination, no filters needed). Source path differs by which dir you pointed at:
inclusions = [
{source="config", destination="config"},
{source="defaultconfigs", destination="defaultconfigs"},
{source="modernfix", destination="modernfix"},
{source="mods", destination="mods"},
{source="scripts", destination="scripts"}
]
inclusions = [
{source="overrides/config", destination="config"},
{source="overrides/defaultconfigs", destination="defaultconfigs"},
{source="overrides/mods", destination="mods"},
{source="overrides/scripts", destination="scripts"},
{source="overrides/options.txt", destination="options.txt"}
]
Add every directory the modpack wants to carry to the server. Inspect the directory you pointed at to find what to include (ls on it).
4. Generate server pack
java -jar ~/spc/spc.jar -config ~/ServerPackCreator/configs/<name>.conf \
--destination ~/spc/output
Output:
~/spc/output/ — flat server dir~/spc/output_server_pack.zip — ready-to-upload zip
Verifying it worked
ls ~/spc/output/
unzip -l ~/spc/output_server_pack.zip
Log lines to look for (success):
ConfigurationHandler.kt: Config check successful. No errors encountered.
ServerPackHandler.kt: Copying files to the server pack...
ServerPackHandler.kt: Creating zip archive of serverpack...
ServerPackHandler.kt: Finished creation of zip archive.
Successfully generated Server Pack: ...
Pitfalls
| Symptom | Cause | Fix |
|---|
SPC headless tty ioctl error in background log | Hermes sandbox kills the process | Run java -jar ... < /dev/null > log 2>&1 foreground with timeout 600; 5–10 min runtime is normal |
curl/gh release downloads truncated to ~33MB of 78MB | gh release asset URL has JWT expiry; WSL proxy is slow | Download via Windows browser to C:\Users\po\Downloads\, then cp to WSL |
No directories or files specified | inclusions = [] from -cgen | See Step 3 above |
Can not connect to maven.legacyfabric.net warnings | LegacyFabric maven is slow/unreliable from CN | Warnings only — ignore if forge-manifest.json/fabric-manifest.xml say "does not need to be refreshed" |
Output server pack has no minecraft_server.jar / forge-*-installer.jar | SPC 8.x does NOT auto-install server jar; it only packages mods/config/scripts | First server boot (./start.sh) downloads them; needs internet. For offline: pre-download to output/ manually |
WSL cp 240MB+ zip to /mnt/e/ stalls | NTFS mount is slow/unstable for big single files | Use PowerShell: Copy-Item '\\wsl$\<distro>\home\po\spc\output_server_pack.zip' C:\Users\po\Downloads\ |
Notes for re-runs
- Home dir
~/ServerPackCreator/ is created on first run; reused after
- Manifests cached in
~/ServerPackCreator/manifests/; refresh ~daily
- Re-running with same conf is safe (default
cleanupOfAlreadyExistingServerPacks=true)
- For CurForge modpacks the source dir is the modpack root, not
overrides/ — adjust inclusions accordingly
⚠️ Real-world behavior gap (SPC 8.x with Modrinth modpacks)
Tested against Chapter of Yuusha 3 (1.20.1 + Forge 47.4.13, Modrinth, 316 client mods):
- modrinth manifest listed 281 mods; SPC output had only 38 mods
- The other 278 were stripped (SPC 8.x's clientside-only fallback list is aggressive — it classifies most content mods as client-only)
- Of the 38, 8 were missing transitive deps; 3 more missing second-order deps (geckolib / patchouli / caelus)
- Net: server still 232 mods short of a complete server pack
Don't trust SPC output as complete for Modrinth modpacks. SPC 8.x was redesigned to only download mods listed in the modpack manifest from the upstream registry — it does NOT include extras from the local overrides/ mods folder even if the user has them. The workflow above is the packaging mechanics; this section is the operational reality.
When SPC output is incomplete — manual scp fallback
The client install (the one the player launches) always has the full mod set. When the server is missing mods, fix by copying from client to server, not by re-running SPC.
- SSH into the server, read the boot log, find the "Missing or unsupported mod" line
- Match the mod name to a jar in the client mods/ directory
scp it to the server's mods/- Restart; repeat for the next missing mod
This is faster than re-running SPC for a deployed server. Use SPC for the initial server pack; use scp for patching.
Nuclear option when many mods are missing: scp client/mods/*.jar server:/.../mods/. Server will load client-only mods (JEI, OptiFine, Iris) as server-side no-ops or warnings, but the world will boot.
See references/spc-8x-modrinth-gap.md for the full Chapter of Yuusha 3 transcript (mod counts, dep chains, exact scp command).
