Introduction

Welcome to the Modded Minecraft Guide. This guide is designed to serve players, server operators, and modpack creators alike.

Debugging

Logs

The easiest way to get help debugging your issue is usually by sharing your game logs with others. Best practice when providing logs is to fully close Minecraft and your launcher, relaunch your game and make it crash again, then provide your logs to others. This makes tracking your issue or crash easier as the log file is much smaller.

There are three common types of logs used to help debug issues:

• Minecraft game logs that can usually be found under logs in your modpack folder. These are named latest.log or debug.log (if you have file extensions disabled they will appear as latest and debug in your folder).

• Crash reports that can usually be found under crash-reports in your modpack folder. These are named crash-DATETIME-client.txt or crash-DATETIME-server.txt.

• Java Runtime crashes that can usually be found in the root of your modpack folder. These are named hs_err_pid####.log. This file can contain access tokens used by Minecraft, do not post this file online.

Logs can be provided as-is in their original file format.

Common issues

My server is lagging

• Open a ticket with your server's hosting provider if they offer support. They have access to your server directly and can find the culprit more easily.

• A common source of consistent lag can be caused by chunk generation when players are exploring the world and creating new chunks. Install the Chunk Pregenerator mod and run this command:

  • /pregen start gen radius <any_name_for_the_task> CIRCLE 0 0 <chunk_radius_to_pregenerate>

  • Remember that chunks are 16 blocks wide, so setting the chunk radius to 100 will generate chunks out to 1600 blocks from spawn (100 x 16) in all directions. Start with a number like 100 and then build from there. The bigger the radius you choose the longer it will take, some radiuses may take hours. This is normal, and you should run this when your players are offline for the best performance.

• Many modern modpacks come with the Spark mod pre-installed (and if not, install it in your server's mods folder). Load into your server and follow these steps:

  • Run /spark profiler start

  • Play the game for a minute

  • Run /spark profiler stop

My singleplayer world is lagging

• Is your hardware good enough to run the modpack? Large modpacks can be intensive on an underpowered computer.

  • Most modpacks require you to allocate between 4-8GB of memory (RAM). If your system only has 8GB or less you may be running into issues.

  • Make sure you have a discrete GPU (such as Nvidia or AMD) to have the best experience playing modded Minecraft. If you don't you may run into issues, especially playing on larger modpacks.

• Many modern modpacks come with the Spark mod pre-installed (and if not, install it in your modpack's mods folder). Load into your world and follow these steps:

  • Run /spark profiler start

  • Play the game for a minute

  • Run /spark profiler stop

My game crashed and I have a file called hs_err_pidXXXX.log in my modpack folder now

Open the log with any text editor. Check for the mention of atio6axx.dll under Problematic frame:, if you find it it means there's a problem with an AMD driver on your computer.

• If you use an AMD video card, you need to update drivers for it.

• If you don't have an AMD video card but have an AMD CPU, your computer may be using your integrated GPU instead of your dedicated GPU. Make sure your monitor is plugged into your GPU and not your motherboard. If that's not the issue, Google "Nvidia changing preferred GPU".

Screen turns black when holding items

Using integrated graphics (iGPU) seems to cause this issue with older versions of Minecraft, most commonly on version 1.7. You can try updating your iGPU drivers, installing a discrete GPU (e.g. RTX 3060) or making sure Minecraft is using your discrete GPU.

• NVIDIA GPU

  • Open your NVIDIA Control Panel.
  • Click Manage 3D Settings.
  • Click Program Settings in the tabs on the right.
  • Select the executable that you want to change the GPU for (i.e. the javaw.exe that your Minecraft instance is using).
  • Under Preferred graphics processor select your Nvidia video card.

• AMD GPU

  • Read AMD's article on Switchable Graphics to learn how to make your computer use your discrete GPU for specific programs. You'll need to force the javaw.exe that your specific Minecraft instance uses use your discrete GPU.

FTB App

The FTB App is the first-party software for installing FTB modpacks, ensuring the FTB modpacks you download are in their intended form and have the most up-to-date versions available. The FTB App also supports CurseForge modpacks, and downloads CurseForge mods using the CurseForge API to support mod developers.

Files and folders

How to find the default folder

• Windows

  • Press Windows + R and type %localappdata%/.ftba.

• MacOS

  • Open a new Terminal and type open ~/Library/Application\ Support/.ftba.

• Linux

  • Navigate to the ~/.ftba directory.

Folder contents

• /.doh_cache - Folder for DNS over HTTPS, containing DNS communication information

• /bin

  • /assets - Minecraft assets
  • /libraries - launcher related files
  • /runtime - Java binaries
  • /versions - Forge jars

• /instances - Folders for each modpack you have installed

• /logs

  • debug.log - Verbose logs that were recorded while the FTB App was last open
  • latest.log - Logs that were recorded while the FTB App was last open

• /storage - Stores a JSON file with version information

• profiles.json - Stores profile information for Minecraft and Xbox, including tokens

• subprocess.pid - Stores a process ID

Modpack folders

• Found on the modpack's page in the FTB App, clicking Settings, and clicking Open Folder at the bottom.

Providing logs

Logs can be provided in one of two ways:

1. Manually providing your logs found in the next section.

2. Using a tool FTB distributes to share your logs to others called the FTB Debug tool. This tool has instructions and is available for several operating systems and architectures:

   • Windows

   • Windows (Arm)

   • MacOS

   • MacOS (Arm/M1/M2)

   • Linux

   • Linux (Arm)

Which logs should I send?

My server is having issues:

• For server logs, you'll have to know where you put your server's folder, or find it on your hosting provider's control panel or through FTP (depending on your host).

• Reference the general logs section and provide your latest.log and any crash reports that were created at the time the server crashed.

My Minecraft client is having issues:

• FTB modpack folders can be found by opening the modpack's page in the FTB App, clicking Settings on the right, then click Open Folder at the bottom.

• Reference the general logs section and provide your latest.log, any crash reports that were created at the time you crashed, and look for any Java runtime crashes.

My FTB App is having issues:

• In your FTB App's folder look for a folder called logs, open it and find a file called latest.log or latest.

Logs can be provided as-is in their original file format.

FTB App common issues

Solutions for common issues that can occur during the use of the FTB App.

FTB-AUTH Errors

The FTB App says I don't own Minecraft

Make sure you own Minecraft on a Microsoft account. If you bought Minecraft when it was still using Mojang accounts, there was a deadline on Sept. 19th, 2023 to migrate to a Microsoft account. If you did not migrate, you do not own Minecraft anymore and will be unable to login with your Mojang credentials. Microsoft did send out a mercy email on that day which will allow anyone that didn't meet the deadline to get a new Minecraft account attached to their Microsoft account, up to 90 days from the deadline.

An error occurred whilst launching... Failed to execute asset update task

Check the latest.log file in the FTB App folder for lines that say:

Tried URL: 'https://resources.download.minecraft.net/blah/blahblahblah...'

Take note specifically of the /blah/blahblahblah part, and if you have multiple Tried URL lines only pay attention ones with unique blah/blahblahblah portions. It is a vanilla Minecraft file that the launcher requires:

1. In File Explorer navigate to C:/Users/<your_username>/AppData/Local/.ftba/bin/assets/objects and find the folder with the first blah in the URL (if the URL ended in /e8/e8fddnjabdsf find the e8 folder and then the file called e8fddnjabdsf).

2. Delete this file and relaunch the FTB App.

Trying to sign in through Microsoft is giving me "We can't find the FTB App"

Using Brave or Safari browsers often cause issues signing into the FTB App. Try disabling Brave Shield or use a different browser. Copy the URL at the top and paste it into another browser of your choice.

Caused by: java.security.cert.CertificateNotYetValidException in debug.log

Your computer's date and time are set incorrectly. Allow Windows to set it automatically for you.

Haven't found your issue?

Take a look at the general modded Minecraft errors that are not specific to the FTB App.