Missing mod dependency (mod requires X which is not present)
Every mod declares which other mods it needs in order to work — in Fabric that's fabric.mod.json's 'depends' block, in Forge it's mods.toml's [[dependencies]]. When the loader finds a mod but can't find one of its declared dependencies, it refuses to start. The error names the missing dependency, so the fix is usually one extra mod download.
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How to fix it
- 1
Read the error to find the exact missing mod
The crash or log message says something like 'Mod sodium requires fabric-api version >=0.90, but it is not present' or 'Dependency for mod betterend: [origins] was not met'. The part in brackets or after 'requires' is what you need to install.
- 2
Download the missing mod from CurseForge or Modrinth
Search for the mod ID or name on the same platform you used for the rest of your pack. Pick the version that matches your Minecraft version and loader. If the dependency is an API library (Fabric API, Architectury, Cloth Config, Patchouli) it's almost always on CurseForge and Modrinth by its full name.
- 3
Check for version mismatches after installing
The loader also verifies version ranges. 'requires sodium ≥ 0.5.3 but found 0.5.1' means the installed dependency is too old — update it to a newer build. Common APIs (Fabric API, Architectury) always have a 'latest for MC X.Y' release that satisfies nearly all callers.
- 4
Reinstall the whole pack from a launcher if this cascades
Missing a core library like Fabric API causes everything that depends on it to fail with the same error. Rather than hunting each dependency manually, reinstall the modpack from the launcher (CurseForge, ATLauncher, Prism) to restore the whole matched dependency tree at once.
Alternative causes
These can produce the same error message — worth ruling out if the steps above don't resolve it.
Mod accidentally deleted from mods/
If the pack was working yesterday, someone may have deleted or accidentally excluded the dependency mod during a cleanup. Check the mods/ directory against what the pack manifest expects.
Client-only mod on a server
Some mods explicitly require a client-side companion that's forbidden on servers (shader packs, HUD mods). If the dependency is client-only, the server can't install it — remove the calling mod instead, or find its server-compatible sibling.
Frequently asked
How do I know which version of a dependency to install?
Look at the calling mod's page on CurseForge or Modrinth — most list their required dependency versions in 'Relations' or the description. If in doubt, install the latest version of the dependency for your MC version; it's almost always compatible.
Can a missing dependency cause crashes later instead of at startup?
No — Forge and Fabric both abort at the dependency check phase, before any game code runs. If the server started fine but crashed later, the issue is something else.
Why doesn't the launcher handle this automatically?
Launchers that install CurseForge or Modrinth packs do pull dependencies automatically via the manifest. Manual mod installs don't. If you added a mod by hand, you're responsible for its dependencies.
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Last reviewed 2026-06-15. If a step is wrong or out of date, tell us — we'll fix the article and the auto-pattern at the same time.