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Troubleshooting & FAQ

This page lists some common problems when installing or running NeoForge modpacks. If your problem isn't covered here, please see the Getting Support section.

Installing Java or NeoForge​

I downloaded the installer file, but I have no way of running it!​

Please see the Installing Java section. Yes, even if you already have Minecraft: Java Edition installed.

I installed Java, but I'm still getting the wrong version!​

This likely means that your PATH variable is not set, or set incorrectly. The PATH variable is a system variable that tells your computer where to find Java. To fix it, do the following depending on your operating system:

Download and run the Jarfix program.

I am getting an error saying "Could not find or load main class @user_jvm_args.txt", what do I do?​

There are two common reasons for this:

  • You are running an outdated version of Java. Please see the Installing Java section.
  • You have multiple versions of Java installed on your computer, possibly installed one of them just right now, but your computer is still using the old one. This means that your PATH variable is not set correctly. Please follow the steps outlined here.

Playing NeoForge​

Early Display Errors​

If you are reading this, you were most likely redirected here by an error message that appeared early during startup. The reason for that is that something went wrong when trying to build the "early loading progress" window, which commonly means that something is wrong with your system's graphics settings.

  • Refer to Minecraft's own video and graphics issues FAQ and go through the steps outlined there.
  • If that doesn't help, try updating your graphics drivers. See I am having visual issues! below.
  • If that too doesn't help, come talk to us on the Discord server because something is very clearly wrong. As a workaround, however:
    • Open your instance folder. If you use a third-party launcher, they will usually provide a button labelled something like "Open Instance Folder". If you are using the vanilla launcher, use the folder you set in the modded profile.
    • Navigate into the config folder.
    • Open the fml.toml file with your favorite text editor (e.g. Windows Notepad).
    • Change the line earlyWindowControl=true to earlyWindowControl=false.
    • Save the changed file.
    • Try starting the game again.

My game is lagging! What can I do?​

Identify whether the problem is on the server or the client (or both).

My server is lagging! What can I do?​

There is multiple reasons why this could be. A common offender are too many entities (= mobs or dropped items) or block entities (= chests, machines, etc.) being nearby.

If you want an exact breakdown of what is lagging, try using the Spark mod. Spark is a profiler that can tell you what code paths are taking how long. To use it:

  • Join a world.
  • Run the /spark profiler command.
  • Wait a couple of minutes.
  • Run the /spark profiler --stop command.
  • Open the link and have a look or, if you can't make any sense of it, post it in the Discord server's #user-support channel and we will try our best to help you.

My client is lagging! What can I do?​

This is commonly because Minecraft is not a very optimized game, and mods can make this worse.

If you are running shaders, chances are that your graphics card is not strong enough to support them. Try disabling shaders and see if this resolves the issue.

If you want an exact breakdown of what is lagging, try using the Spark mod. Spark is a profiler that can tell you what code paths are taking how long. To use it:

  • Join a world.
  • Run the /sparkc profiler command. (Note the use of /sparkc, as opposed to /spark to profile the server.)
  • Wait a couple of minutes.
  • Run the /sparkc profiler --stop command.
  • Open the link and have a look or, if you can't make any sense of it, post it in the Discord server's #user-support channel and we will try our best to help you.

How do I find a faulty mod?​

If you need to find a faulty mod without any lead on where to start, your best bet may be to use a binary search. The binary search is a common way to find a faulty things among many, without going through things one by one. Reworded for mods, it goes as follows:

  1. Remove half of the existing mods and put them into a different folder.
    • Make sure that dependencies (mods requiring other mods) remain intact.
  2. Run the game.
  3. Find out if the issue still exists.
    • If yes: Repeat from step 1 with the current mods in place.
    • If no: Swap out the most recently added mods with the ones most recently set aside, and repeat from step 1.
  4. Repeat this until you found the problematic mod(s).

I am having visual issues!​

Visual issues are often caused by outdated graphics drivers. Please update your graphics drivers, depending on your graphics card brand: AMD | Intel | NVIDIA

If your issue still persists after updating your graphics drivers, see Getting Support.

Getting Support​

If your problem isn't covered here, you should feel free to join the Discord server and ask for help in the #user-support channel. When doing so, please provide the following info if you can:

  • A log (special kind of text file).
    • If you have an issue during installation, the log is found in the same location as the installer itself, with .jar (or .log if you have file extensions enabled) appended to its name.
    • If you have an issue during gameplay, the logs are found in your instance folder. Go into the logs folder and use the file called debug, or debug.log if you have file extensions enabled.
  • A Spark report, in the event that you made one.

There is no debug.log!​

If you are using the CurseForge app to play, it is possible that the app disabled the debug.log file being created. If that is the case, you need to re-enable it. To do so:

  • Open the Settings (gear icon at the bottom left).
  • Under Game-Specific Settings, navigate to Minecraft.
  • Under Advanced, toggle on the "Enable Forge debug.log" option.

Then, re-launch the game to provide a fresh debug.log.

If you are not using CurseForge, or if you are using CurseForge and have enabled the logging option but there's still no debug.log, it is possible that the game crashes before a debug.log can even be created. In this case, a launcher log can help us instead.

To get a launcher log, open your .minecraft folder and find the launcher_log file (or launcher_log.txt if you have file extensions enabled).

Where is my .minecraft folder?​

Depending on your operating system, the .minecraft folder can be found at the following location:

%APPDATA%\.minecraft