How to update a modpack to Minecraft 26.3

Where mods are right now

61.7% of the top 300 Fabric mods have a release for 26.3; 55.3% of the top 300 NeoForge mods have a release for 26.3. The rest have only a beta, exist on another loader, or have no build yet. A pack of 50 mods almost always has a few of each. The 26.3 readiness page tracks this daily.

Back up the whole instance

Copy the instance folder, not just the world: saves/ holds your worlds and config/ holds settings you will want back. If a world is opened without a mod that added its blocks or items, those blocks and items can be lost as the chunks load and save. The backup is how you undo that.

Check every mod against 26.3

Drop your mods folder or .mrpack into the analyzer. Files are hashed in your browser; only the hashes go to Modrinth. Each mod gets one status, and each status has one next step:

• Update. A release for 26.3 exists. Install that build.
• Pre-release only. Only a beta or alpha exists. Fine for testing, risky for a long-running world.
• Replace. No build, but a checked replacement has one. Read what it covers before swapping.
• Remove / continue without. The mod is obsolete or safe to drop on 26.3.
• No release yet. Nothing to install. Wait, or drop it (see below).
• Loader blocker. A 26.3 build exists, but only for another loader.
• Grouped. An addon or library that moves together with its parent mod; decide for the parent.

Replacements that already work on 26.3

Mods without a 26.3 build where a checked replacement has a release:

• Just Enough Items (JEI) → Roughly Enough Items (REI) (alternative)
• ModernFix → ModernFix-mVUS (fork)
• Simple Voice Chat → Plasmo Voice (alternative)
• Oculus → Iris Shaders (loader alternative)
• Embeddium → Sodium (loader alternative)

Mods you can simply remove

Some popular mods do nothing on 26.3 because vanilla or another mod took over their job:

• Cubes Without Borders: For modern Minecraft, Fabulously Optimized considers this functionality redundant because vanilla now exposes an Exclusive Fullscreen option/non-exclusive fullscreen behavior.
• Indium: Sodium 0.6.0 and later support the Fabric Rendering API themselves. Indium's own page says it is no longer required and is not compatible with Sodium 0.6.0+.
• LazyDFU: LazyDFU delayed DataFixerUpper start-up work. Its author notes that since Minecraft 1.19.4 Mojang optimized this enough that the mod is no longer necessary, and it is only maintained for older versions.
• Memory Leak Fix: The author states that every memory leak the mod fixed has been fixed in Minecraft 1.20.5 and later, which makes the mod obsolete there.
• Model Gap Fix: Fabulously Optimized documents model-gap removal as available in vanilla since Minecraft 1.21.11.
• Starlight: Mojang rewrote the light engine in 1.20 using Starlight's core ideas. The author archived the mod, calling it unnecessary on 1.20 and later; its code lives on in Moonrise.

Mods with no build: wait or drop

It depends on what the mod adds. A content mod (blocks, items, mobs, structures, biomes) is part of your world: dropping it deletes what it placed. Either wait for its update or start a new world without it. A client-side mod (performance, interface, visuals) leaves nothing in the world, so you can drop it and add it back later.

The most-downloaded mods still missing a 26.3 build:

Libraries come with their mods

Libraries (YUNG's API, Moonlight, owo-lib and similar) add nothing on their own. They update when the mods that need them do, and you can remove one once nothing in the pack requires it. The analyzer groups them with those mods, so they do not count as separate blockers.

Install and test

Create a new instance for 26.3 with the same loader, add the updated mods, and start a new test world first. If it loads, open a copy of your real world and look around the areas that use modded blocks. Only then play the real world. If a mod you need is still waiting, the share link from the analyzer keeps the whole plan, so you can check back later without the files.