By Evan Lee Salim 
Zcash has officially advanced to a critical stage in its protocol development lifecycle, activating its highly anticipated NU7 network upgrade on the public testnet. This major milestone moves months of planning and developer discussions into a live testing environment, giving the Zcash ecosystem a crucial window of roughly several weeks to evaluate the protocol changes under real-world conditions before a potential mainnet rollout in November.
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 upgrade—was successfully mined on Oct. 4 at 18:21:45 UTC. Shortly after the block was recorded on the ledger, the official Zcash account confirmed the milestone in a public post on the social media platform X, verifying that the NU7 upgrade was officially live and operating on the testnet.
The NU7 upgrade represents the next major network evolution for Zcash, introducing a comprehensive suite of modifications designed to enhance the protocol’s performance, user experience, and long-term economic sustainability. Among the most notable changes included in the upgrade is a significant overhaul of the network’s block time structure. Specifically, NU7 seeks to reduce Zcash’s target block spacing from the historical 75 seconds down to a much faster 25 seconds. By accelerating block production, the upgrade aims to deliver quicker transaction confirmation times for users, thereby improving the overall responsiveness and utility of the cryptocurrency for everyday transactions and peer-to-peer transfers.
In addition to faster blocks, the NU7 upgrade introduces several important structural and cryptographic adjustments. The protocol changes include the complete disabling of version 4 transactions, a technical shift designed to streamline the codebase and phase out older transaction formats in favor of more modern, efficient standards. Furthermore, the upgrade integrates a novel Network Sustainability Mechanism. This mechanism is engineered to redirect a predetermined portion of transaction fees into future block rewards, establishing a more resilient and self-sustaining economic model to support the network’s long-term security and miner incentives.
However, the discontinuation of version 4 transactions carries significant implications for users holding funds in legacy accounts. Specifically, disabling these older transaction formats means that any ZEC currently held within Zcash’s legacy Sprout shielded pool will become entirely unspendable once the upgrade is fully enacted, unless users take proactive steps to move their funds out of the pool prior to the full activation of NU7. This transition underscores the importance of community awareness and timely action as the network prepares for the mainnet phase.
Following the successful testnet deployment, the Zcash Foundation issued a statement on Friday encouraging testnet operators, node runners, and developers to utilize the newly released candidate to test NU7 under genuine network conditions. The foundation emphasized that this live testing phase is an essential procedural step, allowing the developer community to closely monitor performance metrics, identify potential bugs or edge cases, and thoroughly assess the stability of the 25-second block interval before committing to a mainnet release.
The timeline leading up to the mainnet deployment is tightly structured. Zcash developers are scheduled to convene on Oct. 20 to review the performance data gathered from the testnet environment. During this meeting, the core development team will make a final, formal decision regarding whether to proceed with the mainnet activation and will set the precise activation block height. If the testnet evaluation proceeds smoothly without encountering critical obstacles, the mainnet activation for NU7 is currently targeted for Nov. 5, marking another major chapter in the ongoing development of the privacy-focused cryptocurrency network.
Nana Wu 
Ali Ikhwan