How to Fix Missing Mods (MissingModsException)

If you or your players are being kicked from your Minecraft server with a MissingModsException error, it means the server is running mods that your local game client is missing, or vice-versa.

To fix this connection issue, you must ensure that the mods folder on your computer perfectly matches the mods folder on your server.

Step 1: Identify the Missing Mods

The error message displayed on your game's disconnect screen—or printed in your server's console—will typically list the exact names of the missing mods. Take note of these mods, as you will need to track them down to ensure both the client and server share the exact same files.

Step 2: Stop Your Server in the Game Panel

Before adding, deleting, or modifying any mod files, you must stop the server to prevent file corruption or crashes.

1. Log in to your My Cubes Game Panel.
2. Select your server.
3. Click the Stop button on the console page and wait for it to mark as Offline.

Step 3: Update and Verify Server Mods

If the error states that the server is missing the mods, you need to upload them.

1. Navigate to the File Manager in the My Cubes Game Panel (or connect via SFTP using the credentials found in your Settings tab).
2. Open your server's mods folder.
3. Drag and drop the missing .jar mod files from your computer directly into the panel to upload them. (Alternatively, delete the mods from the server if they were added by mistake).

Step 4: Update and Verify Client Mods

If the error states that your client (your personal computer) is missing the mods, you need to add them to your local game files.

1. Locate your local mods folder:

• Custom Launchers (CurseForge, Prism, etc.): Right-click your modpack profile and select Open Folder.
• Windows Vanilla Launcher: Open your start menu, type %AppData%\.minecraft\mods, and press Enter.

2. Place the missing mod .jar files into this folder.

Pro-Tip (Version Matching): Having the same mod isn't enough—you must have the exact same version of the mod. If your server is running jei-1.20.1-15.2.0.jar and your client is running jei-1.20.1-15.3.1.jar, the server will reject your connection. Ensure the file names match perfectly!

Step 5: Restart the Server and Client

1. Once you have verified that the .jar files match perfectly on both sides, return to the Console page in the My Cubes Game Panel.
2. Click Start to boot up the server.
3. Restart your local Minecraft client so it can load the newly added mods into your game.

Connect to your server! If the issue persists after syncing the folders, double-check your server console for any specific mod dependency errors, or verify that the mods you downloaded are meant for your exact server loader (Forge, Fabric, or NeoForge).