Installation

Nytheria is a Minecraft 1.21.1 modpack for Fabric, and the CurseForge app installs all of it for you, including Java 21. This page is for anyone who has not played the pack yet: it covers the requirements, the install, the memory setting, the first start, updates and the basics of a server. <!-- src: M §1, §5 -->

Before you start#

You need Minecraft Java Edition and the CurseForge app. The versions below are installed by the pack, so you do not install any of them yourself. <!-- src: M §1 (Java installed by the app), §5 install route -->

The pack asks for a lot of memory because it loads several hundred mods and a large world generator. The pack's own notes say the live memory use in play is 6 to 7 GB, and a resource reload late in a long session needs about 9 to 10 GB. Below 8 GB the pack is not supported. <!-- src: M §4.3 (user_jvm_args.txt header) -->

Install with the CurseForge app#

Install the pack from the CurseForge app, which downloads the mods, the configuration and Java in one go. <!-- src: M §5 install route -->

1. Install the CurseForge app and open it.
2. Choose Minecraft as the game.
3. Open Browse Modpacks, search for Nytheria and click Install. The project page is also linked here: Nytheria on CurseForge (coming soon).
4. Wait until the download is done. The app installs Java 21 as part of this.
5. Before the first start, set the memory (next section).
6. Click Play and log in to your Minecraft account in the launcher if asked.

The instance lives in the app's folder for Minecraft instances, in a folder named after the pack profile. To open it, use the profile's menu in the app. <!-- src: M §5 instance folder (CurseForge default: <user>\curseforge\minecraft\Instances<profile name>) -->

Set the memory#

Set the memory to 10 GB (10,240 MB) before you play, because the CurseForge app starts the game with its own default and does not read the pack's memory file. <!-- src: M §4.3 "What CurseForge does" -->

1. In the app, open the profile options of the Nytheria profile.
2. Move the memory slider to 10,240 MB.
3. Save the options.

If your PC cannot give the game 10 GB, give it at least 8,192 MB. That is the lowest value the pack supports. <!-- src: M §4.3 -->

Two helpers watch the value for you:

• Memory Settings shows a warning when the game has less than 4,096 MB or more than 12,288 MB, and when your value is more than 30 percent away from its own recommendation table. <!-- src: M §4.3 (memorysettings.json: minimumClient 4096, maximumClient 12288, warningTolerance 30) -->
• TickMender shows a hint on the title screen with the recommended Java arguments. It adds "This modpack runs best with 10 GB of memory" only when the game has less than 10,000 MB and the PC has at least 16,000 MB of RAM. <!-- src: M §4.3 In-game hint -->

Do not give the game all of your RAM. Windows and your other programs need memory too. For the 10 GB recommendation, a PC with 16 GB of RAM is the practical starting point, because the hint above is only shown to PCs from 16,000 MB up. <!-- src: M §4.3 In-game hint (the 16,000 MB condition) -->

Optional Java arguments#

The pack ships a tuned line of Java arguments for garbage collection. They are optional: the pack starts without them. They are meant to reduce long pauses while the game runs. <!-- src: M §4.3 Shipped G1 line, Measured results -->

The CurseForge app does not read the pack's user_jvm_args.txt, so you add the line yourself. Open the profile options in the app and paste it into the field for additional arguments. Keep using the memory slider for the memory, and do not add -Xmx or -Xms to the line. <!-- src: M §4.3 What CurseForge does; TickMender hint "never contains -Xmx/-Xms" -->

-Xss1M -XX:+UseG1GC -XX:+UnlockExperimentalVMOptions -XX:+AlwaysPreTouch -XX:+DisableExplicitGC -XX:+PerfDisableSharedMem -XX:MaxGCPauseMillis=40 -XX:G1HeapRegionSize=16M -XX:G1NewSizePercent=23 -XX:G1ReservePercent=20 -XX:SurvivorRatio=32 -XX:G1MixedGCCountTarget=3 -XX:G1HeapWastePercent=20 -XX:InitiatingHeapOccupancyPercent=15 -XX:MaxTenuringThreshold=1 -XX:+UseStringDeduplication

According to the pack's own measurements, this G1 line beats the ZGC and AppCDS alternatives. At 8 GB, a long flight still has one or two full garbage collections of 1.2 to 1.9 seconds, whatever arguments you use. That is why the pack recommends 10 GB. <!-- src: M §4.3 Measured results -->

The first start#

The first start is slower than later ones. The pack loads several hundred mods, and Sporran (Navrelis's fork of Kilt, made by the Sporran Team) remaps four NeoForge mods once, which adds roughly 30 to 40 seconds the first time. <!-- src: M §5 First start; M §3.3; M Unverified 9, 16 -->

On the first start you will see:

• A custom main menu from FancyMenu and a loading screen from Drippy Loading Screen. The main menu has a button for reporting bugs that opens the Nytheria Discord, and one for BisectHosting if you need a server. <!-- src: M §5 First start, Main menu buttons -->
• Starting settings from Polybind, which merges the pack's default options into your options once and then leaves your own changes alone. <!-- src: M §4.3 Default video settings (merged once by Polybind) -->
• A shader setup from Iris Shaders. The pack preselects the Complementary Unbound plus Euphoria Patches preset and starts with shaders switched off. Press K to turn shaders on or off. The combined preset is built by Euphoria Patcher when the game starts. <!-- src: M §4.2 -->
• New worlds use the Normal difficulty and the BetterX world type, which the pack forces on the world-creation screen. <!-- src: M Re-confirmed unchanged (default difficulty normal); W §2 / world.md world type row (force_default_world_preset) -->

When the main menu is up, continue with Getting Started. <!-- src: IA page structure -->

Updating the pack#

When a new version is out, the CurseForge app offers an update on the pack. Make a copy of your worlds before you press it. <!-- src: M §5 Back up worlds before updates -->

1. Open the pack folder from the profile menu of the app.
2. Copy the world folders from saves somewhere safe.
3. Update the pack in the app.
4. Open your world once and look around before you play for hours.

The pack's files do not include your worlds, your options.txt or user_jvm_args.txt, so an update does not bring its own copies of them. Polybind applies pack defaults once and keeps what you changed. <!-- src: M §5 What the client export contains; M §4.3 -->

Server basics#

You can play with friends without a server: open your singleplayer world to the network with e4mc, which needs no port forwarding. For a permanent world, run a dedicated server or rent one. Running a Server and Multiplayer cover the details. <!-- src: M §5 Share without a server -->

A server needs the following. <!-- src: M §5 -->

Item	Value
Java	21
Minecraft	1.21.1
Fabric Loader	0.19.5 (the server pack uses installer 1.1.2)
Game port	25565 TCP
Voice chat port	24454 UDP (Simple Voice Chat)
Memory	10G in the server pack's variables.txt; the machine needs about 25 % more than that
Template defaults	Normal difficulty, 10 players, online mode on, view and simulation distance 10

Keep three rules in mind:

• Server and players need the same mod versions. QuestBridge and Sporran must be on the server and on every client. QuestBridge 2.0.0 needs GeckoLib 4.9.3 or newer, which the pack includes. <!-- src: M §5 Hosting panel note; M Unverified 6 -->
• Only mods that run on the server belong there. Of the 405 jars, 56 are marked client-only (for example Sodium), one is marked server-only, 344 declare both sides, and the four NeoForge jars declare nothing. The server pack builder removes client-only mods itself. <!-- src: M §1 side split; M §5 Server pack builder -->
• Hosting panels must start fabric-server-launch.jar or fabric-server-1.21.1-0.19.5.jar. <!-- src: M §5 Hosting panel note -->

Common problems#

The game crashes or freezes after some time. Memory is the usual cause. Check the slider against the table above and read Troubleshooting. <!-- src: M §4.3 -->

The frame rate is low. Press K to switch shaders off, lower the render distance and read Performance & Shaders. <!-- src: M §4.2 (K toggles shaders) -->

The pack does not install or start. Restart the CurseForge app and install again. Back up saves before you delete a profile. <!-- src: M §5 (saves) -->

A friend cannot join. Everyone needs the same pack version, including the Sporran layer and QuestBridge. <!-- src: M §5 Hosting panel note -->

A key does nothing or opens a wheel. Several actions share one key through a wheel. See Controls. <!-- src: CQ §1.4 -->

If nothing helps, ask on Discord and look at the FAQ. <!-- src: M §6.1 Discord link -->

See also#

• Getting Started - the first steps after the main menu
• Performance & Shaders - video settings and shader packs
• Running a Server - the dedicated server in detail
• Multiplayer - friends, teams and claims
• Troubleshooting - startup and crash problems
• Controls - keys and wheels