Zcash NU7 Upgrade May Leave Sprout Funds Unspendable

Legacy Zcash funds face restriction in November upgrade

Zcash users holding funds in the network’s legacy "Sprout" shielded pool are being warned that they may lose the ability to spend those coins. The proposed NU7 upgrade, planned for November, would stop accepting the older transaction format used by Sprout.

Under the current system, Sprout allows users to protect the privacy of their transactions. If funds are left in this specific pool after the upgrade, they will become unspendable on the network. The upgrade does not burn or steal the funds, but it effectively locks them away unless access is restored later.

Key details of the proposal

• The NU7 upgrade is based on Zcash Improvement Proposal-2003 (ZIP-2003).
• The change disables version 4 transactions, which are required for Sprout.
• Funds in the Sprout pool will not be lost, but they will be unspendable after the upgrade activates.
• There is a warning that holders may never be able to spend funds left in the pool again.

Warnings from the community and co-founder

Zcash co-founder Zooko Wilcox shared the warning on the social media platform X. He advised users to take action before the upgrade takes effect.

Additionally, a user named "vaspholdings" posted on the Zcash Community Forum, urging holders to check their old wallets. These wallets may contain Sprout ZEC, transparent ZEC, or both. The user noted that only the funds sitting in the Sprout pool are at risk of becoming unspendable.

Timeline and other changes

The NU7 upgrade is scheduled to activate on the Zcash test network (a version of the blockchain used for testing) on October 6. The main network, where actual transactions occur, is targeted for activation on November 5, pending a decision on October 20.

Beyond the Sprout restriction, the upgrade will reduce the target block time from 75 seconds to 25 seconds. This change is intended to speed up transaction processing. The upgrade also includes changes to the issuance of new ZEC coins but plans to preserve the existing halving schedule.

Market context

At the time of reporting, ZEC was trading at $1,627.82. The price was up 8% in the past 24 hours and nearly 40% over the past week, according to data from CoinGecko.

What this means for Zcash users

Users with old Zcash wallets should verify if they hold any Sprout funds. If they do, they should consider moving them to a more recent shielded protocol before the November upgrade. Failure to do so could result in permanent loss of access to those specific coins.

Sources

• Cointelegraph