The official launcher will run mods. It will not babysit them.

You install a loader from its own site, let it create a launcher profile, then drop matching jars into that profile’s mods folder. Mixing Fabric and Forge in one folder is how you get a black screen and a 200-line log.

Minecraft mobs and gear artwork used for mods and loaders section

Safe sequence

  1. Launch the vanilla version you want to mod once, using an official installation. That proves the account, the runtime, and the version JSON download.
  2. Close the launcher. Download Fabric from fabricmc.net, NeoForge from neoforged.net, or Forge from files.minecraftforge.net — not a “mod installer” ad page.
  3. Run the installer, pick the same Minecraft version, leave Create profile enabled.
  4. In the launcher, edit that profile and set a separate game directory.
  5. Play once, quit, then copy mods into mods. Fabric packs almost always need Fabric API as well.

Version matching is the whole game

A 1.21.4 Fabric mod will not load on 1.21.1. A Forge jar will not load on Fabric. The launcher will still show Play. The log in logs/latest.log is where the mismatch is written down.

Resource packs go in resourcepacks. Shader packs need Iris (Fabric) or the shader path your loader documents. Bedrock “mods” in the launcher are Marketplace add-ons, not these jars.

If the game dies on Play: crash guide. If Java goes missing after you set a custom executable: runtime guide.