Confirm the exact game target
The supplied archive path references a 1.20.1 branch. Treat that as a version constraint, not a suggestion. A build for another generation may not load even if the filename looks similar.
Match the loader and dependencies
Identify the loader expected by the build and install only dependency versions that match both that loader and Minecraft version.
Create a reversible test setup
Duplicate your launcher profile or create a new one, back up worlds separately, then launch the loader once before adding the mod.
Verify the first launch
Open a test world, create something small and review logs before moving an important world or adding optional addons.
Practical takeaway
Keep the setup reversible. A separate profile, a world backup and a written record of versions make updates and troubleshooting far easier than reconstructing a working environment after several changes.
Continue with the compatibility overview or review the Valkyrien Skies Mod FAQ .