The problem
Fix crashes caused by missing libraries such as Fabric API, Citadel, Balm or Curios. Find which dependency is missing and install the right version.
Possible causes
- A mod needs a library mod that is not installed.
- The library is installed but its version is too old or too new.
- The library is for a different loader or Minecraft version.
How to identify the cause
- Fabric says "requires any version of X, which is missing" and names the mod that needs it.
- Forge and NeoForge show "Missing or unsupported mandatory dependencies" followed by each mod ID and the version range it needs.
- Use the dependency finder to see what each mod in our library needs.
Step-by-step fix
- Note the dependency name and version range from the error.
- Download that dependency from its official page for your Minecraft version and loader.
- Put it in the
modsfolder with the mod that needs it. - If the error says the version is wrong, replace the dependency with a version inside the range shown.
- Launch again; repeat if a second dependency is reported.
If that did not work
- Launchers such as Prism Launcher and the Modrinth App can install required dependencies automatically when you add a mod through them.
Affected versions
All modded Minecraft versions.
Frequently asked questions
Why does a mod need Fabric API?
Fabric API provides shared hooks that most Fabric mods use. Almost every Fabric instance needs it.
What is a mod ID?
The internal name of a mod, often lowercase without spaces, such as citadel or balm. Search the ID on Modrinth or CurseForge to find the mod.