Zcash has officially activated its highly anticipated NU7 network upgrade on the testnet, marking a major milestone that transitions the protocol’s planned changes into a live testing environment approximately one month ahead of its targeted mainnet deployment.
According to data from the Zcash testnet block explorer ZecBlock, block 4,465,026—which served as the scheduled activation point for NU7—was successfully mined on Oct. 4 at 18:21:45 UTC. The Zcash development team quickly confirmed the milestone to the broader cryptocurrency community, taking to the social media platform X to announce that NU7 was officially live on the testnet and operating as intended.
This testnet activation represents a critical phase in the lifecycle of the NU7 upgrade, which stands as Zcash’s next major network evolution. The upgrade introduces several substantial changes to the underlying protocol, with the most notable being a dramatic reduction in the network’s target block spacing. Currently, Zcash blocks are mined at a target rate of roughly 75 seconds. Under the proposed NU7 parameters, this target will be slashed down to just 25 seconds, a move designed to significantly improve transaction throughput and user experience by speeding up confirmation times across the network.
Beyond the block time reduction, NU7 brings other fundamental protocol modifications. The upgrade completely disables version 4 transactions, an architectural change that modernizes the blockchain’s transaction handling capabilities. Additionally, NU7 integrates a Network Sustainability Mechanism, a feature engineered to redirect a portion of network transaction fees back into future block rewards, thereby securing long-term economic stability and sustainability for the protocol and its miners.
However, the disabling of version 4 transactions carries critical implications for holders of Zcash’s native cryptocurrency, ZEC. Specifically, any ZEC currently held within Zcash’s legacy Sprout shielded pool will become entirely unspendable once the upgrade takes full effect. To prevent permanent loss or locked funds, users holding assets in the legacy Sprout pool must proactively move their funds to newer, supported address formats before NU7 fully activates on the mainnet.
Following the successful deployment on the testnet, the Zcash Foundation issued a statement on Friday urging testnet operators, node runners, and ecosystem developers to utilize the newly released release candidate to test NU7 thoroughly under real-world conditions. This sandbox phase provides developers and stakeholders with a vital window to assess the stability, performance, and security of the upgrade before committing to a permanent mainnet activation.
The insights and data gathered during this testnet trial period will dictate the final timeline for the mainnet launch. Zcash developers are officially scheduled to convene on Oct. 20 to review the performance of NU7 on the testnet. Based on their practical experience and empirical data collected over the preceding weeks, the development team will make a final, formal decision on whether to proceed with mainnet activation and formally set the precise mainnet activation height.
As currently scheduled, the mainnet rollout for NU7 is targeted for Nov. 5, pending the successful conclusion of the ongoing testnet evaluation period and final consensus among core contributors and network participants.
