Class Loader Fixer

Fixes the Class Loader in legacy Minecraft Forge

766 Downloads

forgeutility

Rent Server with this Mod

About this Mod

Summary

This mod fixes the Class Loader in legacy versions of Minecraft.

Details

This is a simple jar-mod which adds the CodeSource to each loaded class in FML.
That is actually everything this mod does (well, besides fixing a few more bugs on even older versions of Forge).
This mod just ships a backported RelaunchClassLoader which overwrites the built-in version (from FML) and allows mods to read the file source of classes.

Why is this needed in some cases?

For example, Block Helper is able to show you in the item tooltips which mod a given item is from.
This procedure relies on the CodeSource object of the ProtectionDomains of the loaded classes.
Old versions of FML do not set this CodeSource, which leads Block Helper into thinking that everything is a Vanilla item.

Installation

As a ModLoaderMP / Forge mod

This mod needs to be installed as a jar-mod. That means, you have to...

Be sure to back up your minecraft.jar!
Extract the content of the mod zip into the minecraft.jar file
Delete the META-INF folder in there
Overwrite any existing files when doing so!
???
Profit!

As a Fabric mod

I do not have any Fabric versions available. However, the fix is incorporated directly into Fabricated Legacy Forge. Hence, you do not need to install it separately!

Unsupported mods

ObsidiPlates 1.4.2 was incompatible with v1. This is fixed in v2.

Please let me know about any incompatibilities! :)

Available Versions

ClassLoaderFixer-2release

MC 1.3.1, 1.3.2, 1.4, 1.4.1, 1.4.2, 1.4.3, 1.4.4, 1.4.5forge

July 4, 2024

1.3.1-1release

MC 1.3.1forge

January 22, 2024

1.4.5-1release

MC 1.4.4, 1.4.5forge

February 11, 2022

1.4.3-1release

MC 1.4.3forge

February 11, 2022

1.4.2-1release

MC 1.4.1, 1.4.2forge

February 11, 2022

How to Install Class Loader Fixer on Your Server

Order Server

Order a Minecraft Java server with at least 3 GB RAM (4 GB recommended).

Set forge Loader

In the panel under "Egg", select the forge loader and matching Minecraft version (1.4.5).

Install Mod

Open the mod browser in the dashboard and search for "Class Loader Fixer". Click "Install" – done! Alternatively, upload the .jar via SFTP to the /mods folder.

Compatibility

Mod Loaders

forge

Minecraft Versions

1.4.5, 1.4.4, 1.4.3 (+5 more)

Server-side

✗ Unsupported

Recommended RAM

4 GB(min. 3 GB)

Frequently Asked Questions

Class Loader Fixer server crashes on startup – what to do?

Most common cause: wrong forge version or insufficient RAM. Check the server log (latest.log) for "OutOfMemoryError" or "Mixin" errors. With Mado Hosting: ensure at least 3 GB RAM is allocated and the loader matches the mod version (1.4.5). You can switch loaders with one click in the panel.

Is Class Loader Fixer compatible with forge?

Class Loader Fixer officially supports forge for Minecraft 1.4.5, 1.4.4, 1.4.3. The Mado dashboard automatically detects incompatible loader combinations.

Server lagging with Class Loader Fixer – how to optimize performance?

Recommended RAM: 4 GB (per 8 players). Use /spark profiler to check if Class Loader Fixer consumes the most tick time. Common fixes: reduce server view-distance to 8-10, install "performant" or "starlight" as supplementary mods on Forge. With Mado Hosting, your server runs on NVMe SSDs with dedicated CPU cores for minimal latency.