Zcash Announces NU7 Upgrade with 25-Second Blocks and Sustainability Mechanism
Major network upgrade to reduce block time and ensure continued halving schedule.
1NU7 Upgrade Timeline
The Zcash NU7 upgrade is scheduled for testnet activation on October 6, 2026, with mainnet activation targeted for November 5. A final decision on mainnet activation will be made on October 20 after testnet performance review. The upgrade includes significant changes to block timing and network parameters, with development teams reaching unanimous agreement on the implementation plan.
2Block Time Reduction
NU7 will reduce Zcash's block time from 75 seconds to 25 seconds through ZIP-218 implementation. This threefold reduction aims to decrease transaction confirmation latency and improve user experience for transactions requiring one or two confirmations. The change will also increase consensus bandwidth while maintaining similar time-based behavior through adjusted network parameters.
3Infrastructure Adjustments
The faster block schedule requires changes to block encryption and network parameters. ZIP-218 proposes increasing the proof-of-work goldrush window from 17 to 102 blocks to maintain smoothing time close to desired wall clock time. Full nodes, indexers, and block explorers will need updates, though ordinary wallets won't require major modifications as NU7 maintains existing transaction types.
4Halving Schedule Preservation
NU7 maintains Zcash's existing ZEC halving structure, with previously stopped issuance resuming in February 2031. The upgrade incorporates the Network Sustainability Mechanism based on September 2026 community sentiment results, which showed strong support for both the 25-second blocks and maintaining the halving schedule as key network features.
5Transaction Version Removal
The upgrade will remove transaction version 4 from the Zcash protocol, a decision made after consultations with ecosystem organizations including Zcash Foundation, Tachyon, Valar, ZODL, and Shielded Labs. This change reflects ongoing optimization efforts while maintaining backward compatibility with existing transaction types and wallet functionality.
6Developer Consensus
All Zcash development organizations reached unanimous agreement on NU7's contents and timeline following community sentiment collection. The upgrade represents coordinated work across multiple engineering teams and reflects both technical improvements and community priorities regarding network performance and sustainability mechanisms.
7Testnet Implementation
NU7 features will be implemented on testnet by September 30, 2026, with official testnet activation on October 6. Developers will use this period to evaluate performance before finalizing mainnet activation parameters on October 20. This phased approach allows for thorough testing of the reduced block time and other network changes.
8Network Sustainability Impact
The NU7 upgrade addresses both immediate performance needs and long-term network sustainability. The combination of faster block times and maintained halving schedule balances transaction speed with predictable issuance, while the Network Sustainability Mechanism ensures continued development funding. These changes position Zcash for both improved usability and enduring ecosystem health.