Author: Deep Tide TechFlow

Introduction: On November 5, 2026, Beijing time, the privacy public chain Zcash confirmed that it will officially activate the network upgrade code-named NU 7 at block height 3,543,405. According to reports, this upgrade will not only compress the on-chain target block time from 75 seconds directly to 25 seconds but will also completely disable version 4 transaction formats, leading to about 12,226 ZEC currently stuck in the first-generation privacy pool Sprout (total estimated value of about 16 million USD) losing all transfer channels, facing indefinite blockage at the protocol level.

Clearing First-Generation Privacy Pool Technology, Ending Version 4 Transaction Format

One of the core changes of the NU 7 upgrade is the abolition of underlying compatibility support for version 4 (v4) transaction formats. This transaction format is currently the only technical channel for funds to be transferred out of the first-generation privacy pool Sprout, which was launched in October 2016. With the arrival of the upgrade block height, full nodes will directly refuse to pack any transfer requests based on the v4 format. Even if the owner of the coin address fully possesses the valid private key, the system will no longer provide a valid signature and broadcasting verification path for that privacy pool.

Early zero-knowledge proof technology bears a heavy technical burden. The Sprout privacy pool relies on the original trusted setup established in 2016, and its proof generation consumes a significant amount of memory and time. With the subsequent launches of the Sapling and the Orchard privacy pools based on Halo 2, which do not require a trusted setup, the Zcash core development team is pushing to clear technical debt by opting to cut maintenance compatibility with the first-generation architecture and completely strip outdated cryptographic lines.

Millions of Sleeping Assets Accumulate, Final Window Period to Escape the Cliff

On-chain statistics show that there are still about 12,226 ZEC trapped in the Sprout privacy pool. Based on a market price of approximately 1,300 USD per ZEC, the total market value of the trapped funds is about 16 million USD. Although the network upgrade notice was issued in advance, the large-scale transfer of these funds has stalled the day before the deadline.

In the past week, about 10,037 ZEC have been migrated out of the first-generation privacy pool through an emergency channel, with a net outflow of 9,094 ZEC on a single day last Sunday. As of Wednesday, the daily outflow amount has sharply dropped from a peak to only about 40 ZEC. The sudden drop in the outflow curve reflects that the holders of the remaining funds have failed to respond to the upgrade window, as the vast majority of trapped tokens belong to early users who lost their private keys, whose owners are missing, or are static sleeping tokens that have stagnated in cold storage.

Theoretical Patches Retained in Standards, Assets Effectively Frozen Permanently

For the trapped assets that cannot be migrated, the developer community has passed the ZIP 2003 improvement proposal. This standard reserves space in the protocol logic for subsequent possible extraction mechanisms, allowing the network to potentially recover the redemption of assets in the Sprout pool through a secondary upgrade in the future. However, the engineering team has included a clear warning in the specification text, stating that this interface only has theoretical feasibility, and the trapped assets are highly likely to never be retrievable.

In the generational transition of privacy assets, Zcash has officially completed the leap from Sprout to a modern funding pool. Currently, the vast majority of active privacy transfers have concentrated in the Orchard and Sapling pools, and the retirement of the old pool has achieved comprehensive isolation from the attack surface of outdated protocols while ensuring the safety of the funds of the existing majority of users.

Block Time Compressed to 25 Seconds, On-Chain Throughput Achieves Doubling Reconstruction

While clearing technical debt, NU 7 has made structural adjustments to the whole Zcash network's block time parameters. The target block time across the network has been compressed from the original 75 seconds to 25 seconds, increasing the block generation speed to three times the original. The significant reduction in block time directly reduces the waiting time for users sending privacy transactions, lowering on-chain settlement delays.

The final countdown for the network upgrade activation is locked at block height 3,543,405, and all network nodes are awaiting the block broadcast at this height to complete the immediate switch of consensus rules.

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