Zcash NU7 upgrade to lock $16 million in Sprout pool on November 5

The Zcash NU7 network upgrade is set to activate at block 3,543,405, expected around 9:30 p.m. Eastern on November 5, 2026. This update will render the remaining funds in the legacy Sprout privacy pool unspendable, impacting approximately 12,224 ZEC, valued near $15 million to $16 million based on recent ZEC prices around $1,230 per coin.

NU7 to Freeze Sprout Privacy Pool

NU7, short for “Network Upgrade 7,” marks a significant milestone for Zcash, a privacy-focused cryptocurrency launched in 2016 to provide confidential financial transactions using advanced cryptographic techniques. The new upgrade follows a series of rule changes coded for activation on the blockchain, rather than at a specific time, to ensure precision across all network participants.

Technical documents ZIP 2003 and ZIP 259 specify that NU7 will block all version-4 transactions, the only format capable of transferring Sprout pool balances. After activation, no residual funds in Sprout will be transferable, even if holders retain their private keys, as consensus rules will reject any attempt to move those assets.

ZIP 2003 clarifies that while Sprout coins are not destroyed or removed from supply, owners should treat them as permanently locked from the moment NU7 activates, unless a future upgrade re-enables their movement.

According to current chain data, Sapling, Orchard, and transparent ZEC funds are unaffected by this decision. Only legacy Sprout balances will become inaccessible, while all other forms of ZEC remain fully spendable under newer transaction formats.

Mini dictionary: Sprout pool — The original shielded pool in Zcash’s privacy design, introduced to provide confidential transfers. Newer privacy pools, such as Sapling and Orchard, improve efficiency and privacy while phasing out Sprout due to technical limitations.

Technical Changes: Block Time and Fee Distribution

NU7 brings another substantial adjustment by reducing the network’s target block interval from 75 seconds to 25 seconds. This means new blocks will appear three times faster, lowering the typical time for three confirmations from roughly 3.75 minutes to just 75 seconds.

The network’s total supply cap of 21 million ZEC and the established four-year halving cycle will remain unchanged. Since blocks are generated more frequently, the per-block reward will decrease to keep daily ZEC issuance steady.

ZIP 235, applied through NU7, reroutes 60% of transaction fees into the Network Sustainability Mechanism (NSM), a fund designed to support continued development. Miners will retain the remaining 40% of fees.

Plans call for reissuance of NSM funds at block height 8,939,664, likely to occur in 2031, according to the published mainnet timeline. These changes are intended to bolster long-term network funding and viability.

Context: Broader Privacy Coin Developments

The impending NU7 activation comes amid broader attention on privacy coins from investors and regulators alike. Zcash has not only pioneered privacy technology but is also at the center of ongoing initiatives, such as a recent Zcash ETF filing from Winklevoss Asset Services, which could further spotlight the coin in global markets.

For now, holders of Sprout funds will lose access to roughly $16 million in ZEC unless a future upgrade enables transfers again. Other Zcash users will continue normal operations, with faster blocks and new fee arrangements taking effect after block 3,543,405.