A useful troubleshooting process is an elimination process. Start with the highest-probability mismatch, then narrow the profile until the error disappears.
Crash before the title screen
Check game version, Fabric loader context, required dependencies and duplicate mod files. If the problem began after one update, test by restoring the previous working file.
Read the first useful error
The earliest clear dependency or version error is usually more actionable than later cascading messages.
Missing dependency message
Read the missing dependency name and version requirement carefully. Installing a different branch or an outdated supporting mod may keep the error in place.
Mod is not visible
Confirm that you launched the same profile whose mods folder contains the file. Keep multiple instances clearly named so paths do not become ambiguous.
Blocks or recipes are missing
Make sure the profile completed loading without hidden errors. Then test without recipe-changing data packs or conflicting content mods to isolate the cause.
Performance suddenly drops
Test a clean profile. If performance is normal there, add rendering, shader and optimization mods back gradually until the conflict appears.
Next steps
After confirming your target version, continue with the Download, or browse the full guide library for more setup checks.