// modpack server guide
Better MC (BMC3) server hosting & setup guide
A BMC3 server needs Java 21 and about 9–12 GB of RAM for up to 15 players.
Version 1.21 | Vanilla+ Experience With The Player in Mind | A New Era of Better MC!
Summary from Better MC (BMC3) on Modrinth.
Better MC (BMC3) is a Fabric modpack for Minecraft 1.21.1 (older versions go back to 1.21) with 292 mods. We'd pick our Heavy plan (12 GB) for it.
Quick facts
| Loader | Fabric |
|---|---|
| Minecraft versions | 1.21.1, 1.21 |
| Java needed | Java 21 for Minecraft 1.21.1 Java version chart. |
| Mods | 292 modsCounted from the pack's file list on Modrinth. None are marked client-only. |
| RAM | About 7–7.5 GB for 1–3 playersBy player count. |
| Downloads | 375,321 on Modrinth |
| Last updated | May 18, 2025 (version v30) |
| First published | July 18, 2024 on Modrinth |
| Server support | Required: the pack has mods that must run on the server. |
| Server pack | BMC3_Server_Pack_v45.zipOfficial server pack on CurseForge, for BMC3 [FABRIC] 1.21.1 v45. Checked October 5, 2026. |
| Modrinth tags | adventure, combat, optimization, challenging, kitchen-sink, lightweight |
BMC3 server files
Yes, on CurseForge. Modrinth has no separate server pack for BMC3, but the authors publish one on CurseForge: BMC3_Server_Pack_v45.zip, for BMC3 [FABRIC] 1.21.1 v45 (May 7, 2026).
That's not the version Modrinth has (v30). A server and its players must run the same pack version, so either install the client pack from CurseForge too, or build the server from the Modrinth pack instead.
How much RAM does a BMC3 server need?
| Players online | RAM | DSN plan |
|---|---|---|
| 1–3 players | About 7–7.5 GB | Premium (8 GB) |
| 4–8 players | About 8–9.5 GB | Heavy (12 GB)Premium (8 GB) can do if players stay close. |
| 9–15 players | About 9–12 GB | Heavy (12 GB) |
Estimated from 292 mods on the server with our RAM calculator, not measured: low end if players stay together, high end if they spread out.
By this estimate Premium (8 GB) can run a small group. Our pick below, Heavy, leaves room for more players and for the pack growing with updates.
Set Java's heap (-Xmx) 10–15% under the RAM you have, about -Xmx10500M on 12 GB. Fabric 1.21.1 takes it in the java command (-Xmx), usually in the start script. RAM guide.
BMC3 server requirements
| Java | Java 21 |
|---|---|
| Loader | Fabric for Minecraft 1.21.1 |
| CPU | Fast single-core speed (one main thread). With 292 mods, the first start takes minutes. |
| RAM | About 7–12 GB for 1–15 players (table above) |
| Disk | The server files, a growing world and backups |
| Network | TCP port 25565 open to players |
Recommended plan
Our pick for BMC3
Heavy
12 GB RAM · planned launch price $42/month
At about 292 Fabric mods this is a heavy pack, and 12 GB keeps it clear of out-of-memory crashes.
Ordering is closed until we relaunch. We aren't taking orders or payments while we move to new hardware. Join the launch list and we'll email you when Heavy servers open.
Heavy is our biggest plan. Not sure? Email hello@dsnservers.com.
Planned launch price in USD, billed monthly once ordering opens, with a 7-day refund window.
How to make a BMC3 server on your own PC
What's specific to BMC3, step by step. The full walkthrough for any pack: how to make a modded Minecraft server.
- Install Java 21.
Check with
java -version. Java version chart. - Get the server files.
Download the official server pack,
BMC3_Server_Pack_v45.zip, from CurseForge and unzip it into an empty folder. Make sure your players install the same pack version. - Start it and accept the EULA.
Run the start script in the server files, or
java -jaron the Fabric 1.21.1 server launcher, then seteula=trueineula.txtif you accept Mojang's EULA (EULA step). With 292 mods, the first start takes minutes. - Set the RAM with
-Xmx, sized from the table above. - Let friends connect: forward TCP 25565, or use a tunnel or host behind CGNAT (can't connect?).
Or run BMC3 on DSN
Once we relaunch (join the launch list), on DSN you'd install BMC3 from the panel's Modrinth modpack installer (version v30), pick Java 21 on the Startup tab and accept the EULA in the console. No port forwarding.
How to play BMC3 with friends
Each player installs BMC3 version v30 with the Modrinth App or Prism Launcher, the same version as the server, and adds the server's address under Multiplayer.
Different versions of BMC3 on the server and a client show up as Mismatched mod channel list or mod rejections. Why friends can't join, timeouts included.
Lag and performance on BMC3
Can't keep up! Is the server overloaded? means ticks take longer than 50 ms; more RAM won't fix that once BMC3 has enough (tick lag guide). For BMC3:
- Measure first: spark's
/spark tpsand profiler work on 1.21.1 and name the mod or machine using the tick time. - Distances:
view-distance=8and a lowersimulation-distanceinserver.properties. - Pre-generate: Chunky for 1.21.1,
/chunky radius 3000then/chunky start, before people explore. - Chunk loaders keep machines running with nobody nearby; in a pack this size, dozens add up.
Common BMC3 crashes
What a Fabric 1.21.1 server running BMC3 hits most. For any other error, paste the log into the free crash log analyzer.
- Out of memory. BMC3 (292 mods on the server) needs about 7–7.5 GB for 1–3 players;
java.lang.OutOfMemoryErrormeans it ran out. Out-of-memory fix. - Wrong Java version. BMC3 on Minecraft 1.21.1 needs Java 21. Started on Java 17, it stops with
UnsupportedClassVersionError: ... class file version 65.0, this version of the Java Runtime only recognizes class file versions up to 61.0. Java version fix. - Client-only mod on the server. The BMC3 pack file marks none of its mods client-only, so this usually means one was copied over from a player's mods folder. Check a mods list with the client-or-server-side checker. Client-only mod fix.
- After adding or updating a mod. Mods you add to BMC3 by hand usually crash it with a missing dependency or a mixin conflict.
- Ticking entity or block entity. The crash report names it and gives its coordinates. Ticking entity fix.
Updates and support
Before moving BMC3 past version v30, back up the world: see updating a modpack server without losing your world.
Bugs in BMC3 itself go to its authors: issue tracker, wiki and Discord. Server problems on DSN: hello@dsnservers.com or Discord.
Packs like BMC3
More: all modpack guides and how to make a modded server.
Run BMC3 on DSN when we relaunch.
Our pick, Heavy: 12 GB, planned at $42/month.
DSN Servers isn't affiliated with Better MC (BMC3) or Modrinth. The pack's icon, summary and stats come from Modrinth's public API (checked October 4, 2026).