How to install mods on a Java server (Forge/Fabric) Print

Mods add new blocks, items, mechanics, and performance tweaks to your Minecraft Java server. This guide shows how to install, update, and remove Forge/Fabric mods using the HostByte Game Panel.

Before You Start

• Loader check: Mods require Forge or Fabric (not Spigot/Paper). You can’t mix Forge and Fabric mods in the same server.
• Version matching: The server’s Minecraft version and loader version must match the mods (e.g., Forge 1.20.1 with 1.20.1 Forge mods).
• Dependencies: Many mods require libraries (e.g., Fabric API on Fabric, Architectury, Cloth Config).
• Back up: Create a backup before adding or updating mods.

Step 1: Set the Server to Forge or Fabric

1. Log in to the HostByte Game Panel and open your server.
2. Go to Configuration → Server Actions.
3. Under Edition, choose Forge or Fabric, then pick the exact Minecraft version.
4. (Optional) Use Format for a clean install (this deletes all server files—back up first).

Step 2: Download the Mod Files

• Download .jar files from trusted sources (e.g., Modrinth/CurseForge).
• Make sure each mod matches both the Minecraft version and the loader (Forge or Fabric).
• Collect required dependencies listed on the mod’s page (e.g., Fabric API).

Step 3: Upload Mods to the Server

Option A — File Manager

1. In the panel, open File Manager.
2. Open (or create) the /mods folder in the server root.
3. Upload your mod .jar files into /mods.

Option B — SFTP (recommended for many files)

1. Copy your server’s SFTP Details from the panel.
2. Connect with FileZilla/WinSCP and upload all mod .jar files into /mods.

How to use SFTP: https://www.hostbyte.net/billing/knowledgebase/72/How-to-Connect-via-SFTP.html

Step 4: Start and Verify

1. Click Restart (or Start if offline).
2. Open Console and watch for missing dependency or version mismatch errors.

Client requirement: Most mods are not server-only. Players usually must install the same mods (and versions) on their client to join.

Step 5: Configure Mods

• Many mods generate config files after first run (e.g., /config folder).
• Edit configs via File Manager/SFTP and Restart to apply.
• Some packs include /defaultconfigs or /kubejs (advanced modpacks).

Updating Mods

1. Back up and read the mod’s changelog for breaking changes.
2. Stop the server.
3. Upload the new .jar into /mods and remove the old .jar to avoid duplicates.
4. Start the server and check the console.

Removing Mods

1. Stop the server.
2. Delete the mod’s .jar from /mods.
3. (Optional) Remove related configs or data if you don’t need them.
4. Start the server and verify it boots cleanly.

Common Issues & Fixes

“Missing Mod” or “Mod Rejections” when joining

• Players must install the same mods (and versions) client-side.
• Share a pack/profile (e.g., via Modrinth/CurseForge app) to avoid mismatch.

“Mod X requires Fabric API / Forge >= X.Y.Z”

• Install the listed dependency (e.g., Fabric API) or update your loader version.

Crashes on startup

• Check the latest log (logs/latest.log) for the first real error.
• Remove recently added mods one by one to isolate conflicts.
• Ensure Java runtime matches modpack requirements (many 1.18+ modpacks require Java 17; newer may prefer 21).

Server is laggy after adding mods

• Some mods are heavy. Profile with a tool like spark (if compatible) and remove/replace offenders.
• Consider performance mods appropriate to your loader (e.g., Lithium, Starlight for Fabric/Forge).

Modpacks (Bulk Install)

• If installing a full modpack, upload all .jar files to /mods plus any pack-specific folders (/config, /kubejs, scripts).
• Match the exact Forge/Fabric loader + MC version the pack targets.
• Allocate appropriate RAM/CPU in your plan; large packs need more resources.

Best Practices

• Add mods incrementally and test—so you know which change caused issues.
• Keep a text list of installed mods + versions for staff and quick client syncing.
• Avoid hot-reload; restart after mod changes to prevent memory/registry issues.

Getting Help

• Knowledge Base: See related Java guides (change edition, backups, troubleshooting).
• Support Ticket: Log in to your HostByte account to open a ticket.
• Discord: Join our community:
• Status Page: Check maintenance/outages: status.hostbyte.net.