According to Woofun AI, the NU7 network upgrade proposal submitted by Sean Bowe, the core developer of Zcash, has officially entered the countdown stage. This technical iteration directly caused the existing assets in Sprout's privacy pool to face the risk of being 'soft-frozen' by the protocol layer. As the upgrade date approaches, ZEC held by a large number of early users is in a difficult situation where it cannot be transferred. This asset liquidity crisis caused by technological evolution is reshaping the community's perception of the security of private coin self-custody.
Deconstructed from a technical parameter level, the core goal of the NU7 upgrade is to improve network efficiency and sustainability. Sean Bowe proposed setting the mainnet activation height to block 3,543,405, with a time window of around November 5. The upgrade drastically reduced the block generation interval from 75 seconds to 25 seconds, and the mining rewards for each block were reduced accordingly to one-third of the original, thus maintaining a constant total daily distribution volume and ensuring that the total supply limit of 21 million pieces and the established halving rhythm were not disrupted.
More critical institutional adjustments involve online sustainability funds: 60% of the processing fees generated by each block will be temporarily withdrawn from circulation and put into reserves, and the remaining 40% will be owned by miners. This portion of the reserve assets is planned to begin around February 2031 (corresponding to mainnet block 8,939,664) and be gradually re-released through future miner rewards.
What really caused market anxiety, however, was the ZIP 2003 proposal that was implemented along with the upgrade. The proposal prohibits all transactions in v4 format from NU7 activation. Since Zcash's transaction format has been iterated to mainstream v5 and v6, and v4 only serves the oldest Sprout privacy pool, this ban directly cuts the spending path of 22,309 ZEC in the Sprout pool. These assets have not been destroyed and are still included in the issued supply, but no expenditure interface is provided at the protocol level. ZIP 2003 only leaves a vague statement that 'it may be reopened in the future, but it may never be recovered', and there is no timeline for the restoration of functionality in the current specification.
The real dilemma of migration operations is the double squeeze of time constraints and technical barriers. At press time, 22,263 ZECs remained in the Sprout pool, with a market value of about $30 million. If the coin holder does not complete the transfer before the NU7 upgrade, the assets will face a permanent lock.
However, there are only 14 days left for users to operate, and the migration process is fraught with obstacles. With the popularity of next-generation privacy solutions such as Sapling and Orchard, Sprout has gradually been abandoned by mainstream wallets. Zallet, the new wallet officially promoted, clearly states that it does not support migrating Sprout's donation keys and funds, and users must rely on old tools that still support Sprout (mainly zcashd) and keep the original wallet.dat file to operate. Once a file or key is lost, the asset is unresolved. For users with missing data, the third-party recovery tool Argos offers an alternative path, but it may require a full scan of around 280 GB of block data, which takes several days to process, which is extremely risky within the 14-day extreme window. Even with a successful migration, users still have to face the cost of privacy breaches: According to ZIP 308 rules, Sprout funds cannot be directly transferred to Sapling; they must first go through a transparent value pool, leading to a public record of the transaction amount.
This “if you don't migrate, your assets are frozen, and if you migrate, your privacy is exposed” dilemma, many users are left passive. According to data compiled by Woofun AI, although the Sprout pool accounts for a small share of the existing capital in the overall ecosystem, its migration failure rate may increase significantly due to technical complexity.
Judging from the background of market influence and community governance, the impact of this soft freeze on macro-liquidity was limited, but it has sparked deep governance disputes. 22,000 ZEC accounts for about 0.45% of the network's blocked coins and 0.14% of the circulating supply. Even if all of them cannot be spent, the direct impact on price fluctuations is minimal. Community views are polarized: Optimists believe that Sprout closed new capital inflows as early as 2020 after the Canopy upgrade, only allowing stocks to be moved out, and its usage scenario has already shrunk to a 'dead water'. Banning v4 transactions is a necessary step to clean up the complexity of the agreement and reduce the potential attack surface.
It's worth noting that this isn't a one-sided decision by the developer. In September 2026, the Zcash community held a shareholder governance vote. Approximately 2.4 million ZEC participated. Of these, 99.9% supported reducing the block time to 25 seconds, and clearly supported disabling v4 format transactions in this upgrade. Developers have continued to remind users to migrate over the years. The NU7 upgrade is seen as the deadline for this long migration, and assets that have not been migrated are most likely forgotten or lost.
Opponents point out, however, that this sets a dangerous precedent for privacy coins: users hold private keys but lose the ability to spend assets due to protocol upgrades, which is contrary to the core values of 'Not your keys, not your coins' self-custody core values.
If even basic asset control cannot be guaranteed, the effectiveness of private self-hosting has a 'shelf life' defined by the developer.
The controversy surrounding the NU7 upgrade is essentially a game between technological evolution and user rights. Sean Bowe has hinted that Sapling's retirement may be discussed in the future, which means Sprout's fate is not an exception. There are plenty of technical reasons for Sprout being eliminated today, but if faced with similar situations in the future, will the community still accept the same treatment? For users who still have a Sprout balance, time is running out. The most urgent task is to immediately confirm the wallet status, assess migration costs and privacy risks, and make a final decision before the upgrade takes effect.
This incident not only tests the technical execution of the Zcash community, but will also affect the foundation of the market's trust in the security of private assets over the long term.