How to join a modded Minecraft server

• The name of the modpack and its exact version, or the list of mods if it is not a pack.
• The server address.
• Whether you need to be added to the whitelist.

Use the launcher that hosts the pack. The CurseForge app and the FTB app cover most packs; Prism Launcher and the Modrinth App can install packs from CurseForge and Modrinth too.

1. Install the launcher and sign in with your Microsoft account.
2. Search for the modpack and open it.
3. Choose the same version as the server, not automatically the newest. Most launchers have a version dropdown on the pack page.
4. Install and start it once from the launcher, so it can set everything up.
5. Go to Multiplayer, Add Server, paste the address and join.

Owners who put their own set together often share it as one file. Launchers turn that file into a ready profile:

The file holds the list of mods and their settings, and the launcher downloads the mods themselves. Only import files from an owner you trust, because a pack can contain any mod.

Some servers use a hand picked set of mods instead of a pack. Then you rebuild the same set.

1. In your launcher, create a new profile with the same loader (Fabric, Forge or NeoForge) and the same Minecraft version as the server.
2. Add the same mods, at the same versions. Many owners share a mod list or a small pack file to make this easy.
3. Mods that only change what you see, like a minimap or shaders, are fine to add on your side. Mods that add blocks or items must match the server.

No extra launcher? The normal Minecraft Launcher runs mods too, after one installer:

1. Download the installer of the loader the server uses from its official site: Fabric, Forge or NeoForge.
2. Run it, choose the client install and the Minecraft version of the server. It adds a new installation to the Minecraft Launcher.
3. Put the mod files in the mods folder of your game, shown in the table below. Create the folder if it is not there. On Fabric, most sets also need Fabric API in that folder.
4. Start the new installation from the Minecraft Launcher and join.

This works well for one server. For several modded servers, a launcher such as Prism keeps each set of mods in a profile of its own, so they never get mixed.

Not every modded server needs mods on your side. A Fabric server that only runs server side mods, such as performance mods, Chunky or LuckPerms, lets players in with the normal game. As soon as a mod adds blocks, items or mobs, everyone needs it, and on Forge and NeoForge servers you almost always need the mods.

Ask the owner which kind of server it is. If you guessed wrong, the error table further down tells you quickly.

Your own game needs memory too, separate from the server. Big packs crash or freeze on the default setting.

Set it in your launcher's settings for that profile, usually under Java or Memory. Do not give more than half of your computer's RAM.

The new amount counts from the next start of the game, so close it fully and start again.

Mods that only change what you see, or how the game runs on your computer, can be added without the server having them:

• Performance: Sodium on Fabric and NeoForge, Embeddium on Forge, for more frames per second.
• Shaders, with the shader loader that fits your pack, see the question about shaders below.
• Maps: a minimap such as Xaero's Minimap or JourneyMap.
• Small comforts such as zoom or a nicer chat.

Check the rules of the server first. Mods that give an unfair edge, such as x-ray, are banned almost everywhere, and some servers switch off the cave view of minimaps.

A crash on your side leaves a report in the folder of your profile, in crash-reports, and the full log in logs/latest.log. Most launchers have a button that opens the profile folder.

• A crash before the main menu is mostly memory or a wrong Java; see the memory tables above.
• A crash when you join, while others can play, points at a mod only you have. Remove what you added yourself and try again.
• A crash for everyone at the same spot is a matter for the server. Send the owner the time and the place.

Sending the crash report to the owner, or to the makers of the pack, usually gets an answer faster than describing it.

After a pack update on the server, your old version no longer fits. Update the profile in your launcher to the version number the owner names, not simply to the newest, and join again. The world and your buildings live on the server, so updating costs you nothing.