NeoForge Download and Install: Client, Server and 26.3

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Where to download the NeoForge installer, how to install it on your PC or a server, which build fits 1.21.1 or 26.3, the Java each needs and installer fixes.

A grey Minecraft-style computer block with a command prompt on its screen

You want NeoForge on your PC or a server and need the right file: the official installer, the build that matches your Minecraft version or modpack, and the Java to run it. Below: where to download it, which version fits 1.21.1 packs such as ATM10 or 26.3, the client and server installs, updates and the installer errors that come up most, all checked against NeoForged's own site, docs, maven and installer on 31 October 2026. New to NeoForge? Start with what NeoForge is.

Quick answer: Download NeoForge from neoforged.net: pick your Minecraft and NeoForge version in the "NeoForge installer files" box and click "Click Here to Download Installer". On your PC, run the installer, keep "Install client" selected, click Proceed and start the new NeoForge installation in the Minecraft Launcher. For a server, run java -jar neoforge-<version>-installer.jar --installServer in the server folder, start it with run.sh or run.bat and set eula=true. Minecraft 1.21.1 packs such as ATM10 use NeoForge 21.1.x (newest: 21.1.265) on Java 21; Minecraft 26.3 uses NeoForge 26.3.0.x (newest: 26.3.0.100) on Java 25.

Where to Download NeoForge

The official NeoForge download is the "NeoForge installer files" box on the front page of neoforged.net. Choose a Minecraft version, then a NeoForge version, and click "Click Here to Download Installer". On 31 October 2026 the box opened on Minecraft 26.3 with NeoForge 26.3.0.100. The list also holds snapshot builds such as 26.1-snapshot-11, so pick a plain release number.

The button links straight to NeoForged's maven, where every installer has the same kind of address:

https://maven.neoforged.net/releases/net/neoforged/neoforge/<version>/neoforge-<version>-installer.jar

That makes a NeoForge server download one command:

V=21.1.265
curl -LO https://maven.neoforged.net/releases/net/neoforged/neoforge/$V/neoforge-$V-installer.jar

Next to each installer the maven publishes checksum files (.sha256, .sha1, .sha512, .md5) and a .asc signature. To check your download on Linux:

echo "$(curl -s https://maven.neoforged.net/releases/net/neoforged/neoforge/$V/neoforge-$V-installer.jar.sha256)  neoforge-$V-installer.jar" | sha256sum -c

It prints neoforge-21.1.265-installer.jar: OK when the file matches. On Windows, Get-FileHash .\neoforge-21.1.265-installer.jar in PowerShell shows the SHA256 hash to compare with the .sha256 file. Skip installers rehosted on download portals and file sharing sites; Is NeoForge safe? explains why.

NeoForge 1.21.1, 26.3 and Other Versions: Which One You Need

The NeoForge version number tells you the Minecraft version:

  • Up to 1.21.11: the first two numbers are the last two of Minecraft's. NeoForge 21.1.265 is for Minecraft 1.21.1, and 21.11.48 for 1.21.11.
  • From 26.1 on: versions have four parts. In 26.3.0.100, 26.3.0 is Minecraft 26.3 and 100 is the NeoForge build.

A -beta suffix means, in NeoForged's words, that "breaking changes are still allowed"; it is dropped once the line is stable. This is where each line stood on 31 October 2026:

MinecraftNeoForge lineNewest buildStable sinceJava
1.21.121.1.x21.1.265 (25 Oct)no beta builds21
1.21.1121.11.x21.11.48 (15 Oct)21.11.42 (28 Mar)21
26.1.226.1.2.x26.1.2.125 (29 Oct)26.1.2.71 (2 Jun)25
26.226.2.0.x26.2.0.93 (15 Oct)26.2.0.57 (9 Aug)25
26.326.3.0.x26.3.0.100 (31 Oct)26.3.0.76 (11 Oct)25

Not in the table:

  • NeoForge for 26.1 and 26.1.1 never left beta; the last builds are 26.1.0.19-beta and 26.1.1.15-beta. The stable 26.1 line is 26.1.2.
  • The maven has no NeoForge builds for the 26.4 snapshots yet.
  • For Minecraft 1.20.1, NeoForged's user guide recommends Forge, and NeoForge only from 1.20.2 on.

How to choose. With a modpack, use exactly the build the pack names. All the Mods 10 8.4, released on CurseForge on 29 October 2026, lists Minecraft 1.21.1 and NeoForge 21.1.265 in its manifest. For All the Mods 11, a 26.x pack, our ATM11 server requirements list the build it names. With your own mod list, filter Modrinth or CurseForge by NeoForge and your Minecraft version, and choose the version where every mod you need has a build. Within that Minecraft version, take the newest stable NeoForge build.

To get the newest build from a terminal, ask the maven:

curl -s "https://maven.neoforged.net/api/maven/latest/version/releases/net/neoforged/neoforge?filter=21.1."

{"isSnapshot":false,"version":"21.1.265"}

Keep the trailing dot. Without it, filter=21.1 also matches the 21.11 line and returns 21.11.48. For 26.3, use filter=26.3. the same way.

Install the Right Java First

The Minecraft Launcher downloads its own Java for the game, but that Java does not run the NeoForge installer or a server. NeoForged's user guide says it plainly: "NeoForge requires you to install Java yourself." Mojang's version files name the Java each release needs:

  • Minecraft 1.20.5 to 1.21.11, so 1.21.1 and ATM10 too: Java 21
  • Minecraft 26.1, 26.1.1, 26.1.2, 26.2 and 26.3: Java 25

NeoForged's user guide still lists Java 21 for "1.20.5-latest" (checked 31 October 2026). For 26.x that is out of date: NeoForged's own 26.1 post says "Minecraft is now using Java 25".

Check what you have with java -version. The first number after version is the major version, and the output should mention 64-Bit; NeoForged's guide asks for a 64-bit Java. To install it:

  • Windows: winget install -e --id=Microsoft.OpenJDK.25 (or Microsoft.OpenJDK.21), the same command NeoForged's guide gives for 21, or a JDK installer from Adoptium.
  • Ubuntu 24.04 and Debian 13: sudo apt install openjdk-25-jdk or sudo apt install openjdk-21-jdk.

For more systems, see Minecraft server Java version requirements.

How to Install NeoForge on Your Client

  1. Start the Minecraft Launcher once, then close it. The installer looks for the launcher's profile file in your Minecraft folder and will not install without it.
  2. Double-click the installer .jar, or run java -jar neoforge-21.1.265-installer.jar in a terminal.
  3. Keep "Install client" selected. The path field should show your Minecraft folder: %APPDATA%\.minecraft on Windows, ~/Library/Application Support/minecraft on macOS or ~/.minecraft on Linux. Click Proceed.
  4. Wait until it reports that the client profile was installed. If the vanilla client for that Minecraft version is missing, the installer downloads it itself, so you do not have to play vanilla first.
  5. Open the launcher. A NeoForge installation is now in the list.

NeoForged recommends a separate installation instead of that entry, so your mods stay apart from your vanilla game: open Installations, click New installation, give it a name, choose the NeoForge version, set a game directory outside .minecraft and save it. The mods folder appears in that game directory after the first start; put mods for your NeoForge and Minecraft version there, from CurseForge or Modrinth as NeoForged advises.

If you play through Prism Launcher, the Modrinth App, the CurseForge app or another launcher on NeoForged's list, follow that launcher's own steps instead. NeoForged notes that these launchers "mostly automate this process".

How to Install a NeoForge Server

On Linux, in the folder the server will run from:

mkdir -p ~/neoforge-server && cd ~/neoforge-server
V=21.1.265
curl -LO https://maven.neoforged.net/releases/net/neoforged/neoforge/$V/neoforge-$V-installer.jar
java -jar neoforge-$V-installer.jar --installServer

--install-server does the same. The installer downloads the Minecraft server jar from Mojang and the libraries, then writes:

  • run.sh and run.bat, the start scripts
  • user_jvm_args.txt, for memory and other Java settings
  • libraries/, with the argument files the scripts read, such as libraries/net/neoforged/neoforge/21.1.265/unix_args.txt

Set the memory before the first start: open user_jvm_args.txt and remove the # in front of -Xmx4G. The file calls 4 GB "a good default for a modded server"; large packs ask for more, so use the figure your pack gives. Then start it:

./run.sh nogui

The first start stops after it creates eula.txt. Change eula=false to eula=true to accept the Minecraft EULA and start again. The server listens on port 25565 unless you change server-port in server.properties. On Windows, run .\run.bat the same way. Without a terminal, double-click the installer, choose "Install server", pick an empty folder with the "..." button and click Proceed.

For hosts that only run java -jar server.jar. Add --server-starter (or tick "Server starter jar" in the installer window). The installer then also downloads NeoForged's ServerStarterJar as server.jar, which reads run.sh or run.bat and starts the server in the same process. Its README warns that it does not pick up user_jvm_args.txt by default, so start it like this:

java @user_jvm_args.txt -jar server.jar nogui

Mods and modpacks. The mods folder appears after the first start. Keep client-side mods, such as shader mods, off the server; NeoForged's guide admits that telling which mods are client-side "often requires trial and error". For a modpack, use the pack's own server files where it has them; for ATM10 that is covered in ATM10 server files. Keep your players on the same pack version as the server.

On a Space-Node Minecraft server, NeoForge and popular modpacks install from the panel, and you set the Java version and JVM arguments yourself in the Startup tab.

How to Update NeoForge

Back up your world first, as NeoForged's guide says; on a client the worlds are in the saves folder of the game directory.

  • Client: run the installer for the new build. It points the launcher's NeoForge entry at the new version; in your own installation, choose the new version under Installations.
  • Server: stop the server and run the new installer with --installServer in the same folder. It writes new run.sh and run.bat files that point at the new build and leaves your user_jvm_args.txt alone, because it only writes that file when it is missing. If you edited a start script, make that edit again.

That covers updates within one Minecraft version, such as 21.1.259 to 21.1.265. Moving from 21.1.x to 26.3.0.x is a Minecraft update that needs new mod builds and Java 25; the 26.3 server update guide covers it. On a modpack server, update the pack rather than NeoForge alone, because the pack names its build; see update a modpack without losing your world.

NeoForge Installer Errors and Fixes

Double-clicking the installer does nothing, or another program opens it. Java is missing, or another program has taken over .jar files. Install Java as above, "even if you already have Minecraft: Java Edition installed" as NeoForged's FAQ puts it, or run java -jar on the file from a terminal. On Windows, Jarfix restores the .jar association, and NeoForged's FAQ points to it when the wrong Java keeps running.

"The directory is missing a launcher profile. Please run the Minecraft launcher first." On the command line the installer says "you need to run the launcher first". It found no launcher profile file in the folder: start the Minecraft Launcher once, or set the installer's path to the folder your launcher uses.

"Error: Could not find or load main class @user_jvm_args.txt". The start script ran an old Java. Java 8 cannot read the @ argument files the scripts use; the java command gained them in Java 9. NeoForged's FAQ names two causes: an outdated Java, or a new Java installed while the old one still comes first on your PATH.

The server stops at once with a class file version error. A 26.x server on Java 21 prints:

Error: LinkageError occurred while loading main class net.neoforged.fml.startup.Server
	java.lang.UnsupportedClassVersionError: net/neoforged/fml/startup/Server has been compiled by a more recent version of the Java Runtime (class file version 69.0), this version of the Java Runtime only recognizes class file versions up to 65.0

Class file version 69.0 means Java 25 and 65.0 means Java 21, so install the Java the first number points to. A 1.21.1 server on Java 17 also stops before Minecraft loads, with an error that names version 65.0.

The installer stops while downloading. A broken download ends with "Downloading minecraft server failed, invalid checksum. Try again, or manually place server jar to skip download." If NeoForged's maven is down (see status.neoforged.net), neoforged.net itself tells you to run the installer with --mirror https://maven.creeperhost.net. Each run writes a log named after the installer plus .log, such as neoforge-21.1.265-installer.jar.log, in the folder you ran it from; that is the file NeoForged's support asks for.

FAQ

Where do I download NeoForge? From the "NeoForge installer files" box on neoforged.net. The button downloads from NeoForged's own maven, maven.neoforged.net, which also publishes a SHA256 checksum for every installer.

Which NeoForge version is for Minecraft 1.21.1? The 21.1.x line. On 31 October 2026 the newest build is 21.1.265, the one ATM10 8.4 lists in its manifest, and it runs on Java 21.

Is there NeoForge for Minecraft 26.3? Yes, the 26.3.0.x line. Its builds have had no beta suffix since 26.3.0.76 on 11 October 2026, the newest is 26.3.0.100, and it needs Java 25.

Is there a separate NeoForge server download? No. The same installer does both: choose "Install server" in the window, or run it with --installServer. Add --server-starter if your host needs a server.jar.

How do I update NeoForge? Back up your world and run the installer for the new build the same way as before. On a client, then select the new version in your installation.

Do I need Java if Minecraft already runs on my PC? Yes. The launcher's Java only runs the game. To open the installer or run a server, install Java 21 for 1.21.x or Java 25 for 26.x.

Sources

All opened on 31 October 2026: