The upgrade also introduced a new transaction format supporting the Ironwood shielded pool. Ironwood was developed following the discovery of a critical soundness vulnerability affecting Orchard, Zcash’s previous shielded pool. The issue affected the zero knowledge proof system used to validate Orchard transactions. Users can manually migrate their Orchard funds through the application, while an automated migration system designed to provide stronger privacy protections is expected later. The upgrade follows an emergency network response in June that temporarily restricted Orchard transactions while developers deployed an initial correction through NU6.2.