Zcash’s NU7 Upgrade Goes Live on Testnet Ahead of Targeted November Mainnet Launch

Zcash has officially advanced to the next crucial phase of its protocol evolution, with its anticipated NU7 network upgrade now live on the testnet. This major milestone gives developers, node operators, and the broader community a vital multi-week window to rigorously evaluate a series of fundamental protocol changes, most notably a drastic reduction in block times, before a planned mainnet activation scheduled for November.

According to data from the Zcash testnet block explorer ZecBlock, block 4,465,026—which served as the predetermined activation point for NU7—was successfully mined on Oct. 4 at 18:21:45 UTC. Shortly after the milestone block was processed, the Zcash development team confirmed the successful deployment via a public post on the social media platform X, verifying that the NU7 upgrade is now fully operational in the testnet environment.

The NU7 upgrade represents a comprehensive overhaul designed to optimize the performance, efficiency, and long-term economic sustainability of the privacy-focused blockchain network. Among its most prominent features is a structural change to the network’s target block spacing. Under the current parameters, Zcash targets a 75-second block time. The NU7 upgrade seeks to slash this interval down to just 25 seconds. By accelerating block production by a factor of three, the network aims to significantly improve transaction throughput, responsiveness, and user experience, bringing Zcash closer to the speed demanded by modern decentralized applications and everyday users.

In addition to faster blocks, the NU7 upgrade introduces other critical architectural changes. Most notably, the protocol update disables version 4 transactions entirely. This deprecation of older transaction formats is a necessary step in modernizing the network’s codebase and streamlining future development, but it also carries direct implications for asset holders who have not migrated their funds.

Specifically, disabling version 4 transactions means that any native Zcash tokens held within the network’s legacy Sprout shielded pool will become entirely unspendable once the NU7 upgrade fully activates on the mainnet. To prevent permanent loss of access or locked capital, users holding funds in the legacy Sprout pool are required to actively move their funds out of those addresses and into newer, supported shielding pools before the mainnet activation takes effect.

Furthermore, the NU7 upgrade integrates a newly designed Network Sustainability Mechanism. This economic update is engineered to structurally alter how transaction fees are handled within the ecosystem, redirecting a designated portion of collected transaction fees back into future block rewards. By doing so, the mechanism aims to bolster the economic incentives for miners and secure the network’s long-term operational health without relying solely on traditional block subsidy emissions.

Following the successful deployment on the testnet, the Zcash Foundation issued a statement on Friday urging testnet operators, validators, and community stakeholders to utilize the newly released candidate software to test NU7 thoroughly under real-world conditions. The Foundation emphasized that this dedicated testing phase is essential for identifying any potential edge cases, performance bottlenecks, or unforeseen bugs. The operational data gathered during this period will provide developers with the empirical evidence needed to determine whether the network is fully stable and ready to proceed with the mainnet launch.

The timeline for the final rollout is already locked in motion. Zcash developers are scheduled to convene on Oct. 20 to review the performance data collected from the testnet environment. During this assessment, the development team will make a formal and final decision regarding the mainnet activation and establish the precise activation height. If the testnet phase proceeds smoothly without critical issues, the mainnet activation for the NU7 upgrade is targeted to take place on Nov. 5, marking a significant new chapter for the Zcash network.