--- title: "How to make a Cobblemon server (Pokémon in Minecraft)" description: "Cobblemon has no official server. What you actually need: Fabric, Java 21, the pack on both sides — and the real JVM heap behind the tier you pick." url: https://tickserv.com/en/guides/cobblemon-server site: "TickServ (https://tickserv.com)" lang: en published: 2026-07-17 updated: 2026-08-22 games: [minecraft] --- # How to make a Cobblemon server (Pokémon in Minecraft) Cobblemon adds Pokémon to Minecraft: catching, battling, training, breeding — all in multiplayer. It's a **Fabric** mod, and its official modpack has passed **9.9 million downloads** on Modrinth. One detail the pack's own page states plainly, and it explains why you're looking for a server: **"Cobblemon does NOT have an official server."** There's no public game to join. If you want to play with friends, someone has to host. ## What a "Cobblemon server" actually is Cobblemon is a **content** mod: it adds creatures, items and blocks. A content mod therefore has to be present on **both sides** — server and client — in the **same version**. It isn't a server-side mod you install once and forget. In practice, a Cobblemon server is three things: 1. **A Fabric server** for the right Minecraft version. The official pack (`Cobblemon Official Modpack [Fabric]`) exists for **Minecraft 1.21.1** and **1.20.1**. 2. **The pack's mods** dropped into `mods/`. There is no such thing as a "Cobblemon server download": you get the pack, install a Fabric server, and put the mods in place. 3. **The right Java version.** Since Minecraft 1.20.5, the game requires **Java 21 or newer** ([Minecraft Wiki](https://minecraft.wiki/w/Server/Requirements)). An older Java won't start at all — it fails on `Unsupported class file major version`. The most requested pack after the official one is **COBBLEVERSE**, which is far bigger: more mods, more entities, and roughly double the memory appetite. ## RAM: the number that matters isn't the machine's This is the most common mistake, and nobody spells it out. What runs a Minecraft server isn't the machine's RAM — it's the **JVM heap** (`-Xmx`), which is necessarily **smaller**. The operating system, Docker and Java's own off-heap memory (metaspace, buffers) all live beside the heap. Give everything to the JVM and the kernel will eventually kill your server mid-game. Here, the heap is worked out for you: **the smaller of "RAM − 2 GB" and "75% of RAM"**. Which gives: | Tier you pick | Actual JVM heap | | ------------- | --------------- | | 4 GB | 2 GB | | 8 GB | **6 GB** | | 16 GB | 12 GB | | 32 GB | 24 GB | Now, the official pack's Modrinth page asks for **a minimum of 2.5 GB of memory, and 3 GB or more for best performance**. The 4 GB tier, which leaves only a 2 GB heap, is therefore **below the pack's own minimum**. - **Official pack, small group**: take the **8 GB** tier (6 GB heap). That's the sensible default. - **COBBLEVERSE, add-ons, or a lot of players**: **16 GB**, and the **dedicated CPU** level if exploring stutters. - **4 GB**: fine for vanilla, too tight for Cobblemon. ## The first boot is slow — and that's normal A modded server doesn't start like a vanilla one. On first boot it downloads the pack, resolves mod dependencies, then generates the world. For a big pack, **expect 15 to 25 minutes**. A vanilla server is ready in 1 to 2 minutes. This is phantom failure number one: people assume it has failed, kill it, start again — and never finish that first boot. Later boots are much quicker, the world already being generated. ## The three failures that keep coming back **"Mod mismatch" / connection refused.** The client doesn't have exactly the same pack, or the same pack version, as the server. By far the most frequent cause. Check the pack's version number, not just its name. **`Unsupported class file major version`.** Java too old for that Minecraft version. Since 1.20.5 you need Java 21. **The server holds at spawn, then dies when someone explores.** The classic symptom of an undersized heap: generating fresh world chunks is the single most memory-hungry thing a server does, and a mod that spawns creatures everywhere adds a great many entities to keep track of. The cure is heap, not CPU. ## The two settings that genuinely change something Of the fifteen Minecraft settings available, two carry most of the performance: - **View distance** and **simulation distance** (3 to 32, **10** by default). The second is the expensive one: it's the radius in which the server keeps the world _alive_. Dropping it to **6 or 8** is the cheapest fix for lag — well before adding RAM. - **Spawn protection**, **whitelist** and **operators**, to hold the front door. The rest (difficulty, game mode, PvP, hardcore, Nether, flight, structures, resource pack) is a matter of taste. Player slots default to **20** and go up to 50. ## Your Pokémon, and where they live Captured Pokémon live in the world and player data — not in a separate file. Lose the world and you lose the collection. Treat it accordingly. Here, the data directory is archived **before every shutdown** and restored on the next session, with an automatic backup **every 30 minutes** while you play and the **last 5** kept. The server gets a `save-all flush` before archiving, so no minute of play is left sitting in memory. What is _not_ archived: the server's libraries and binaries, which the image re-downloads each session. Your archive holds only what's yours. ## Here, in two minutes When creating a **Minecraft** server, pick Cobblemon from the modpack list — or paste any Modrinth or CurseForge URL into the **Modpack** field. The loader and version come from the pack: nothing to install by hand, no Java to choose. The game port is the usual **25565**. Port **19132** (the default Bedrock port) is open too: crossplay is neither provided nor supported, but if you install Geyser yourself, the port won't be what stops you. And when the session is over, you shut it down: **server off = €0**. That's what makes a modded server sustainable when you play three evenings a week. > [Create your Minecraft server](https://tickserv.com/en/games/minecraft) and paste the Cobblemon link. Your first session is free.