By Sagoh 
Zcash has officially activated its highly anticipated NU7 network upgrade on the testnet, successfully advancing its planned protocol changes into a live testing environment approximately one month ahead of its targeted mainnet rollout. This milestone represents a critical step forward for the privacy-centric cryptocurrency as developers and node operators prepare to evaluate the sweeping structural changes under real-world conditions.
According to data from the Zcash testnet block explorer ZecBlock, block 4,465,026—which served as NU7’s scheduled activation point—was successfully mined on Oct. 4 at 18:21:45 UTC. The official Zcash team quickly confirmed the successful deployment later that day in a public post shared on X, officially declaring that the NU7 upgrade was live on the testnet and open for evaluation.
The NU7 upgrade stands as Zcash’s next major network evolution, introducing several foundational alterations designed to improve the blockchain’s overall performance, economic model, and transaction processing capabilities. Among the most prominent changes slated for introduction is a substantial reduction in the network’s target block spacing. Currently, Zcash aims for a 75-second block interval, but NU7 seeks to accelerate this timeline dramatically by targeting a 25-second block spacing. This threefold increase in block generation speed is intended to drastically speed up transaction confirmation times for users, aligning Zcash more closely with the responsiveness expected of modern digital assets.
In addition to faster blocks, the NU7 upgrade implements critical housekeeping and economic adjustments. The protocol update officially disables version 4 transactions, phasing out legacy structures in favor of more modern and secure transaction formats. Furthermore, NU7 integrates a newly formulated Network Sustainability Mechanism. This mechanism is engineered to redirect a predetermined portion of transaction fees directly into future block rewards, establishing a more sustainable long-term economic model for the network’s miners and validators as the asset’s overall issuance schedule changes over time.
However, the discontinuation of version 4 transactions carries significant implications for certain legacy asset holders. The decision to disable these older transaction formats means that any ZEC still held within Zcash’s legacy Sprout shielded pool will become entirely unspendable unless users proactively move their funds prior to the full activation of NU7 on the mainnet. This technical cutoff places a time-sensitive requirement on long-term holders who have yet to migrate their assets out of the deprecated Sprout pool, ensuring that historical privacy pools are successfully phased out without stranding user capital unexpectedly, provided those users take action ahead of the deadline.
Following the successful testnet deployment, the Zcash Foundation issued a statement on Friday encouraging all testnet operators and community developers to utilize the newly released software candidate to thoroughly test NU7 under genuine network conditions. This critical testing window allows the developer community to closely monitor network stability, assess the behavior of the accelerated block times, and verify the seamless execution of the Network Sustainability Mechanism before any permanent changes are committed to the primary production environment.
The current testnet phase serves as the final proving ground for developers to assess the upgrade before rendering a definitive decision on whether to proceed with mainnet activation. According to the established development schedule, Zcash core developers are slated to make their final determination regarding the mainnet activation and establish the precise activation block height on Oct. 20. This decision will be informed entirely by the performance data and practical experiences gathered during the ongoing NU7 testnet trial period.
Pending a successful evaluation and final approval by the development team, the mainnet activation for the NU7 upgrade is tentatively targeted for deployment on Nov. 5, marking a major milestone in Zcash’s ongoing technical roadmap.
Nana Wu 
Ali Ikhwan