Zcash NU7 Upgrade to Freeze About 12,224 ZEC in Sprout Privacy Pool

Zcash is preparing to activate its NU7 upgrade, which will make coins left in the old Sprout privacy pool unspendable. According to ZecStats, about 12,224 ZEC remained in Sprout at the start of November, worth roughly $15–16 million at market prices. Activation is scheduled for block 3,543,405. The latest block at the time of publication was 3,543,027, so the switch is expected later the same day, in the evening US time. The exact timing depends on how quickly blocks are mined, not on a calendar.

Why Zcash is freezing coins

Unlike BitcoinБиткоинBitcoin (BTC) is the first and best-known decentralized cryptocurrency, running on its eponymous blockchain network with no central issuer or intermediary bank., Zcash lets users conceal transaction amounts and addresses using zero-knowledge proofs. The Sprout pool launched with the network in 2016. Developers later introduced more advanced privacy systems, including Sapling, Orchard and Ironwood. New depositsДепозитA deposit is a transfer of money from a player or customer to their account with a casino, sportsbook, or exchange operator. Once the funds are credited, they become available for betting or trading. to Sprout have been closed for years, but holders of existing funds could still withdraw them.

NU7 eliminates version-4 transactions, the only format that can move coins out of Sprout. According to the network's technical specification, such transactions will become invalid after activation. The developers say supporting outdated technology adds complexity and potential vulnerabilities, and the old transaction-verification scheme required substantial computing resources.

What changes for ZEC holders

Holders of coins that remain in Sprout are the most exposed. To avoid losing access, they must withdraw funds through a compatible mechanism before the upgrade activates. Sprout addresses start with "zc", which can help identify old wallets. Users of modern, supported wallets do not need to move coins out of Sprout, but keeping their software updated still matters.

The blockchainБлокчейнA blockchain is a distributed database in the form of a chain of blocks, where each record is cryptographically linked to the previous one, and copies are stored by many network participants. does not show who owns the Sprout balance, so it is unknown how much belongs to active users and how much is already inaccessible due to lost keys. The specification explicitly warns that spending these funds may never be re-enabled. Developers stress that the coins are not burned: they will continue to count toward circulating supply calculations, and a future upgrade could theoretically restore access, but this is not guaranteed.

What NU7 means for other users

For everyone else, NU7 brings a change in speed. The target block interval falls from 75 to 25 seconds, so first confirmation of transactions should arrive about three times faster, according to the Zcash Foundation.

Timing

As of publication, the latest available block was 3,543,027. Once the network reaches block 3,543,405, any coins left in the old Sprout pool that have not been withdrawn will be frozen under the new rules.