By Layla Zulfa 
Zcash has officially advanced its highly anticipated NU7 network upgrade to the testnet environment, marking a major milestone for the privacy-focused cryptocurrency project. The transition brings a series of core protocol modifications into live, real-world testing just weeks ahead of a targeted mainnet activation date.
According to data from the Zcash testnet block explorer ZecBlock, block 4,465,026—which was designated as the official activation point for the NU7 protocol changes—was successfully mined on Oct. 4 at 18:21:45 UTC. Shortly after the milestone block was processed, the official Zcash account confirmed the successful deployment in a public post on the social media platform X, verifying that the NU7 upgrade was fully operational on the testnet.
The successful testnet launch provides core developers, node operators, and ecosystem stakeholders with a vital window of time to evaluate the stability, performance, and security of the network under active conditions. This phase is designed to ensure that all proposed adjustments function seamlessly before the community commits to pushing the code live on the mainnet.
At the core of the NU7 upgrade are several structural changes aimed at improving network performance and economic sustainability. Most notably, the upgrade seeks to drastically reduce Zcash’s target block spacing from the current 75 seconds down to just 25 seconds. By accelerating block times, the network aims to significantly improve transaction finality and user experience, bringing processing speeds more in line with contemporary blockchain standards.
In addition to faster block times, the NU7 upgrade introduces critical protocol housekeeping by permanently disabling version 4 transactions. This architectural shift also carries major implications for users holding funds in legacy parts of the network. Specifically, Zcash tokens held within the legacy Sprout shielded pool will become entirely unspendable once the upgrade takes full effect, unless holders actively migrate their assets prior to the activation of NU7. This transition underscores the network’s ongoing evolution away from older cryptographic architectures toward more streamlined and efficient privacy implementations.
Furthermore, the NU7 upgrade integrates a new Network Sustainability Mechanism. This feature is engineered to structurally redirect a designated portion of transaction fees back into future block rewards, creating a more sustainable long-term economic model for the miners and validators who secure the decentralized network.
Following the successful deployment, the Zcash Foundation released a statement emphasizing the importance of the testing period. The foundation urged testnet operators and developers to utilize the release candidate to thoroughly examine the behavior of NU7 under real conditions. This rigorous evaluation period gives the developer community the necessary empirical data to assess the upgrade’s readiness.
The timeline moving forward leaves a narrow window for final assessments. Zcash developers are scheduled to convene on Oct. 20 to review the performance of the testnet deployment and make a final, formal decision regarding mainnet activation. If the testnet phase proceeds without encountering major technical roadblocks, the developers will lock in the exact activation height for the mainnet rollout, which is currently targeted for Nov. 5.
Nana Wu 
Ali Ikhwan