What Memory Leak Fix works with.
| Platform | Java Edition |
|---|---|
| Loaders | Fabric, Forge, Quilt |
| Minecraft versions | 1.14.4, 1.16.5, 1.18.2, 1.19.4, 1.20.4 |
| Environment | Client, Server |
Memory Leak Fix patches a handful of memory leaks in vanilla Minecraft, running automatically on both the client and the server with no configuration and no required dependencies. It supports Fabric, Forge, and Quilt, but every build stops at Minecraft 1.20.4, published in January 2024, so it is not a fit for a current modpack without a plan for what happens on newer versions.
What Memory Leak Fix changes
The mod targets memory that vanilla Minecraft allocates and then fails to release, the kind of leak that lets a long session slowly eat more RAM until performance degrades or the game crashes. It works the moment it is in the mods folder, on both sides of a server, with nothing to configure. FxMorin's own project notes recommend pairing it with Lithium for general performance and FerriteCore for further memory reduction, since none of the three mods overlap in what they fix.
Why development stopped at 1.20.4
This is not a mod that got abandoned mid-project. The creator's release notes state plainly that the leaks Memory Leak Fix patched were fixed inside vanilla Minecraft itself starting with version 1.20.5, which made the mod unnecessary going forward on that front. The source repository on GitHub was archived by its owner in September 2026 and is now read-only, closing the door on any future update even for an unrelated bug. Players on Forge or NeoForge chasing memory leaks in current versions, including leaks introduced by other mods rather than vanilla, should look at AllTheLeaks instead, a separate, actively updated project built to solve the same category of problem. It has no Fabric or Quilt build, so that gap stays open on those loaders.
Supported loaders and versions
- Forge: release build v1.1.5, Minecraft 1.17 through 1.20.4, published January 6, 2024
- Fabric: release build v1.1.5, Minecraft 1.17 through 1.20.4, published January 6, 2024
- Quilt: uses the Fabric build, same version range and release date
- Earlier releases cover Minecraft 1.14.4 through 1.16.5 on the same three loaders
- No required dependencies on any loader
How to tell if a mod is causing a memory leak
A leak looks like memory use climbing steadily over a play session instead of settling once chunks stop loading and never coming back down, eventually slowing the game or crashing it. The most reliable way to isolate the cause in a large modpack is a binary search: remove roughly half the mods, play for ten or fifteen minutes while watching the memory readout on the F3 debug screen, then repeat on whichever half still climbs. A Java profiler such as VisualVM gives a more direct answer by showing which mod's objects keep growing instead of getting collected, for anyone comfortable attaching one to the game process.
Questions about Memory Leak Fix.
5 questions
Does Memory Leak Fix work on the latest Minecraft version?
No. Every build stops at Minecraft 1.20.4, published in January 2024, on Fabric, Forge, and Quilt alike. The creator's own notes say the leaks it targeted were fixed in vanilla Minecraft starting with 1.20.5, so no newer build exists or is planned.
Does Memory Leak Fix need Fabric API or any other dependency?
No. It ships as a single self-contained jar on Fabric, Forge, and Quilt, with no required dependency on any of them. Drop it into the mods folder alongside your other mods and it runs without extra setup.
Is there a maintained alternative to Memory Leak Fix?
For Forge and NeoForge, yes: [AllTheLeaks](/mods/alltheleaks) targets the same category of problem, vanilla, loader, and mod memory leaks, and is still actively updated past 1.21. It has no Fabric or Quilt build, so players on those loaders have no direct drop-in replacement.
How do I find out which mod is causing a memory leak?
Use a binary search. Remove half of your mods, play for a while, and watch whether memory use through the F3 debug screen keeps climbing instead of leveling off. Repeat on whichever half still leaks until one mod is left, or use a Java profiler like VisualVM for a more direct answer.
Can I use Memory Leak Fix in a modpack?
Yes, with credit to FxMorin as the creator. The license does not allow merging its code into another mod or client without separate permission, so keep it as a standalone jar in the modpack rather than bundling its code elsewhere.
