What a dependency error looks like
Fabric commonly reports that mod resolution encountered an incompatible mod set and then lists a mod that requires another mod. Forge and NeoForge may describe a missing mandatory dependency or show required and installed version ranges. The wording differs, but the relationship is the same: one file cannot load until another compatible file is present.
The dependency name in the error may be a technical mod ID rather than the public project title. For example, punctuation and capitalization can differ. Use the project page of the mod that made the requirement and follow its dependency links instead of downloading a similarly named file from an unknown mirror.
Choose the correct dependency build
Match three properties before downloading: Minecraft version, loader family, and dependency version range. A Fabric API JAR cannot satisfy a Forge dependency. A build for Minecraft 1.21 may not work on 1.20.1 even when the filename looks similar.
Do not automatically install the newest file. Install the newest file that explicitly supports your instance. For large modpacks, the pack author may intentionally pin an older library because other mods have not migrated.
When the dependency is already installed
If the log says a dependency is missing even though a similarly named JAR exists, check whether the file is disabled, corrupted, nested in another folder, or built for a different loader. Also look for a version constraint: “missing” can mean the loader found a version that does not satisfy the requirement.
After replacing the file, launch once and read the new log. Do not keep troubleshooting from the old report because line numbers and dependency decisions may have changed.
Quick troubleshooting checklist
- ✓Read the exact required mod ID
- ✓Use the author's official dependency link
- ✓Match Minecraft version
- ✓Match Fabric, Forge, NeoForge, or Quilt
- ✓Respect the required version range
- ✓Relaunch and analyze the new log
Every launch creates a new result. After making one change, use the newly generated latest.log rather than continuing from an older report.