Fabric ModResolutionException: Mod resolution took too long!

What the log looks like

net\.fabricmc\.loader\.discovery\.ModResolutionException: Mod resolution took too long!

How to fix it

1. Update Fabric Loader to the latest version (0.12.0 or newer) in your launcher's version/instance settings, which replaces the legacy mod resolver and removes this 30-second timeout.
2. If you run an application firewall (such as OpenSnitch on Linux or Little Snitch/LuLu on macOS), allow the Java binary used by Minecraft to make local loopback (`127.0.0.1` / `localhost`) DNS and network queries.
3. On macOS or Linux, check `/etc/hosts` and ensure your computer's current hostname is mapped to `127.0.0.1` and `::1` alongside `localhost` so Java does not hang during initialization.
4. Make sure Fabric API and other mods are placed only in the `mods` folder (do not inject them into `minecraft.jar`), and exclude your launcher's instances folder from real-time antivirus scanning if disk access is slow.

Check your own log