Better MC Troubleshooting Guide

The most common cause is using the wrong Java version. Better MC for 1.20.1 (BMC4) and 1.21.1 (BMC5) require Java 17 or newer.

How to check your Java version:

• Open Command Prompt (cmd) and type: java -version
• If it says Java 8 or Java 11, you need to update

How to fix:

• Download Java 17 from Adoptium (adoptium.net)
• Install it, then open your launcher settings
• Make sure the Java path points to your new Java 17 installation

Better MC needs at least 4 GB of RAM allocated to Minecraft. The recommended amount is 6-8 GB.

How to fix:

• Open your launcher and go to the profile/instance settings
• Find the JVM Arguments section
• Set: -Xmx6G -Xms6G for 6 GB allocation
• If you only have 8 GB of system RAM, use -Xmx4G -Xms4G and close other programs before playing

Important: Never allocate more than half of your total system RAM to Minecraft.

Each Better MC version requires a specific mod loader. Make sure you installed the correct one:

• BMC4 (1.20.1) — requires Forge
• BMC5 (1.21.1) — requires NeoForge
• BMC3 / BMC2 — require Fabric for their respective Minecraft versions

Check our versions page to confirm which mod loader your version needs.

This usually happens when you downloaded the wrong file for manual installation.

• The CurseForge manifest (~50 MB) is only for the CurseForge app — it will not work for manual installs
• You need the Server Pack (full ~600 MB file) for manual installation

How to get the correct file:

• Go to the Better MC CurseForge page
• Click Files, then select your version
• Under Additional Files, download the Server Pack

If you are getting low FPS or frequent lag spikes, try these fixes in order:

• Allocate more RAM — 6-8 GB recommended (see OutOfMemoryError fix above)
• Lower render distance to 8-10 chunks in Video Settings
• Disable or lower shader quality if you have shaders enabled
• Close other programs — browsers with many tabs, Discord, streaming software, etc.

Better MC already includes performance optimization mods (Embeddium for Forge versions, Sodium for Fabric versions). These should be active by default.

This is normal behavior on the first visit to any new dimension. The game needs to generate new chunks from scratch.

• Wait 1-2 minutes for initial chunk generation to complete
• Performance will improve once the nearby chunks are loaded
• For servers: use the Chunky mod to pre-generate chunks before players visit a dimension

Large modded structures from mods like When Dungeons Arise and Twilight Forest towers can cause temporary FPS drops.

• Lower your render distance to reduce the number of structure blocks being rendered
• Allocate more RAM if possible (6-8 GB)
• These drops are usually temporary and resolve once the structure is fully loaded

Check our version comparison guide for a full breakdown of every Better MC version.

Short answer: most players should start with BMC4 [FORGE] for Minecraft 1.20.1. It has the most content and the best mod compatibility.

If the CurseForge app is failing to install Better MC:

• Update the CurseForge app to the latest version
• Try clearing the app cache (Settings → Clear Cache)
• Alternative launchers: try Prism Launcher or use the manual installation method from our download page

If you are using a third-party launcher, follow these steps:

• Use the manual installation method with the Server Pack file
• Make sure you have the correct Forge or Fabric version installed for your Better MC version
• Point your game directory to the extracted Server Pack folder
• See our download page for detailed manual installation instructions

If you cannot connect to a Better MC server:

• The client and server must use the exact same modpack version — even a minor version difference will prevent connection
• Check that the server has port 25565 open (or the custom port if configured differently)
• Verify the server IP address is correct
• See our multiplayer guide for more details on setting up and joining servers

All players and the server must use the exact same Better MC version.

• Do not add or remove mods from the pack unless the server also has the same changes
• If the server uses a custom mod list, ask the server admin for their exact modpack file
• After updating, make sure every player and the server update to the same version at the same time