Do NOT update to 15.4 if you care about Rocksmith 2014 working. The issue is independent from the patch and also happens on a vanilla unmodified install of the game.

The inner workings of macOS are incomprehensible, but the work on the patch is mysterious and important. The latest patch works on the beta, I'll test it again on the release candidate build of macOS 26 and if needed recompile/fix the patch before making an actual release.

Rocksmith 2014 uses a DSA signature to verify the authenticity of songs. This app is a runtime patch for Rocksmith 2014 OSX which allows playing custom CDLC content.

See CustomsForge, How to Add Custom Songs on Mac for more info.

If you have problems please join the CustomsForge discord server so we can help you make it work! https://discord.com/invite/cf

Donations: https://paypal.me/starbfly4

Original Injector: https://github.com/rscustom/RSInjector-Mac