Why Run Your Own Server?
Playing Cobblemon on your own server gives you complete control — your own world, your rules, playable whenever you want without depending on public server uptime. When you split the hosting cost between four to six friends, it typically works out to £1–2 per person per month.
There are two ways to do this: self-hosting (run the server on your own PC) or paid hosting (rent a server from a provider). Both work fine. Self-hosting is free but your PC needs to stay on, and port forwarding can be fiddly. Paid hosting is the smoother option for most people.
Self-Hosting vs Paid Hosting
The choice comes down to whether you want free and hands-on, or easy and always-online.
Self-Hosting (Your PC)
- Completely free
- Full control over files and config
- Good for testing or solo play
- Your PC must stay on while others play
- Port forwarding required for outside access
- Your home internet upload speed is the bottleneck
- Higher electricity cost over time
Paid Hosting
- 24/7 uptime — no PC needs to stay on
- One-click Fabric/NeoForge install
- Automatic backups included
- Typically £4–12/month (split between players)
- Costs money (though very little per person)
- Less direct file access than running locally
RAM Requirements
Cobblemon spawns Pokémon as persistent entities with their own AI, which is significantly more CPU and RAM intensive than vanilla Minecraft. Don't underspec this — a server that runs out of memory will crash or lag badly.
| Players | Minimum RAM | Recommended RAM | Notes |
|---|---|---|---|
| 1–4 players | 4 GB | 6 GB | Fine for the base mod + a handful of QoL additions |
| 4–10 players | 6 GB | 8 GB | The sweet spot for a small friend group |
| 10–25 players | 8 GB | 10–12 GB | Add Lithium (Fabric) for extra TPS headroom |
| 25+ players | 12 GB | 16 GB | Consider tuning max-pokemon-per-player |
| COBBLEVERSE modpack | 8 GB | 10–12 GB | This pack is heavy — don't go below 8 GB |
Setting Up a Paid Server (Recommended)
These steps apply to most major Minecraft hosting providers. The UI will differ slightly between them, but the process is the same.
Pick a plan with at least 6 GB RAM for a small group. Most providers list Cobblemon-specific plans. Apex Hosting, BisectHosting, and Sparked Host all have one-click Cobblemon installs. When comparing, prioritise single-core CPU speed over total core count.
In your control panel, go to Software or Game settings and select Fabric. Choose Minecraft version 1.21.1 — this is the version Cobblemon v1.7.x runs on. If your panel has a "Cobblemon modpack" one-click option, you can use that instead and skip step 3.
Download the latest Cobblemon jar and Fabric API from Modrinth. In your control panel, navigate to the /mods folder and upload both files. Cobblemon will not run without Fabric API present.
fabric-api-0.x.x+1.21.1.jar Copy
Start the server from your control panel. It will generate files and then stop, asking you to accept Mojang's EULA. Open eula.txt in your file manager and change eula=false to eula=true. Start the server again — this time it will fully load.
Your server IP is shown in the control panel dashboard — it looks like 123.45.67.89:25565 or a hostname like yourname.apexmc.co. Friends need to have the same version of Cobblemon installed on their client. The easiest way is to share the Official Cobblemon Modpack from Modrinth — it includes everything needed to connect.
To use admin commands in-game, open the Console in your control panel and run:
This gives you access to all Cobblemon admin commands like /pokespawn, /pokegive, and /pokeheal.
Self-Hosting on Your Own PC
Running a server locally is free but requires a bit more setup. You'll need Java 21 installed, and if you want people outside your local network to connect, you'll need to configure port forwarding on your router.
What you need
- Java 21 — download from Adoptium.net
- The Fabric server jar for Minecraft 1.21.1
- The Cobblemon mod jar and Fabric API (both from Modrinth)
- At least 6 GB of free RAM to allocate to the server
Visit adoptium.net and download the latest Java 21 LTS release. Run the installer. Verify it's working by opening a terminal and running java -version — you should see 21.x.x.
Go to fabricmc.net/use/server and download the installer. Run it and select Minecraft version 1.21.1. This creates a fabric-server-launch.jar in your chosen folder.
Create a mods folder in your server directory and add your Cobblemon and Fabric API jars. Then create a start script to launch the server with enough RAM:
Change -Xmx6G to however much RAM you want to allocate. Don't exceed about 80% of your total system RAM.
Double-click your start script (or run it from terminal). It will stop after a few seconds — open eula.txt and change eula=false to eula=true. Run the script again. This time Cobblemon will fully load.
If friends outside your home network need to connect, you need to forward port 25565 (TCP) in your router settings. The exact steps vary by router — search for your router model + "port forwarding". Once done, share your public IP address (find it at whatismyip.com) with your friends.
Recommended Config Tweaks
Cobblemon creates a config file at config/cobblemon/main.json on first launch. These are the settings worth adjusting for a server environment:
| Setting | Recommended Value | What it does |
|---|---|---|
| pokemonPerChunk | 3 | Max Pokémon entities per chunk. Default is 6 — lower this to reduce lag on busier servers. |
| maxPokemonLevel | 100 | Leave at default unless you're running a custom challenge server. |
| shinyRate | 4096 | Base shiny odds. Lower the number to increase shiny rates — popular on friend servers (e.g. 512 or 256). |
| allowSpectatorBattles | true | Lets other players watch battles. Recommended on for community servers. |
| displayEntityNameTags | true | Shows Pokémon names above their heads. Disable if you want a less cluttered world. |
| healTimerTicks | 300 | Ticks between passive Pokémon healing (300 = 15 seconds). Lower for a more casual experience. |
Common Errors & Fixes
Most Cobblemon server problems fall into a handful of categories. Click any error below to see the fix.
This almost always means wrong Java version. Cobblemon 1.21.x requires Java 21. Run java -version in your terminal. If it shows Java 17 or earlier, install Java 21 from adoptium.net and make sure your start script points to the new version.
For self-hosted servers, this is almost always a port forwarding issue. Check that port 25565 (TCP) is forwarded in your router to your PC's local IP. You can verify the port is open using a tool like canyouseeme.org. For hosted servers, double-check your friends are using the exact server IP from your control panel.
First, make sure both the Cobblemon jar and Fabric API are present in the /mods folder — Cobblemon silently fails to load its spawning config if Fabric API is missing. Also check that your server's render distance is at least 5 chunks — Pokémon won't spawn if chunks aren't being loaded. Finally, verify the biome you're in has spawns for that Pokémon using the spawn guide.
The client and server must run the exact same version of Cobblemon. Check your server's /mods folder and make sure every player's client has the matching jar. The simplest fix is to have everyone use the Official Cobblemon Modpack from Modrinth — this keeps versions synchronised automatically.
Three things to try in order: (1) Lower pokemonPerChunk to 3 in config/cobblemon/main.json. (2) Install Lithium in your /mods folder — it improves entity ticking performance significantly. (3) If you're self-hosting, check that you've allocated enough RAM and that your PC isn't thermal throttling.
Battle desyncs usually happen when server TPS drops below 18. This is a performance issue rather than a bug. Address it with the lag fixes above. If TPS is fine but desyncs still occur, check for conflicting mods — some older addons that hook into battle events can cause this. Remove addons one by one to identify the culprit.
You need to allocate more RAM. In your start script, increase the -Xmx value (e.g. change -Xmx6G to -Xmx8G). On a hosted server, upgrade to a plan with more RAM. If you're already on 8 GB+ and still crashing, check for memory leaks from addon mods — some older addons don't clean up properly.
Adding Mods & Addons
Once your server is running, you can add Cobblemon addons and other Fabric mods. The rule is simple: any mod you add to the server must also be on every player's client unless the mod is explicitly marked as "server-side only".
Popular server-side performance mods that don't need to be on client:
- Lithium — general server optimisation, significant TPS improvement
- Chunky — pre-generates chunks so players don't cause lag exploring new areas
- Spark — profiling tool to diagnose where lag is coming from
Mods that must match on client and server:
- Any Cobblemon addon (Mega Evolution, gym badges, custom spawners, etc.)
- Any mod that adds new blocks, items, or biomes
- The Cobblemon mod itself