Modpack installations fail in predictable ways. Version mismatches, missing configs, and wrong loader versions cause 90% of boot errors. Follow these steps in order and you will avoid most of them.

1. Pick the right plan: Most modpacks under 100 mods run fine on Gold (6 GB). Heavier packs with 150-200 mods or a large player count belong on Diamond.

2. Download the server pack, not the client pack: Most modpack platforms (CurseForge, Modrinth, ATLauncher) offer a server pack download. Use that - it strips client-only mods and includes the correct loader installer.

3. Match versions exactly: The Forge or Fabric loader version, Minecraft version, and mod versions must all match. Check the modpack's changelogs if anything looks misaligned.

4. Upload configs alongside mods: If the pack includes a config folder, upload it with the mods. Missing configs cause the server to regenerate incorrect defaults which breaks mod behaviour.

5. Boot once, read the log: Let the server start and crash or complete successfully. Open the latest.log and read from the bottom up. Look for the first real exception - that tells you exactly what failed.

6. Fix missing dependencies first: Most boot failures are a missing mod dependency. Install the required mod at the correct version before changing anything else.