Zcash NU7 upgrade to freeze $16 million in oldest privacy pool

Zcash is executing its NU7 network upgrade at block height 3,543,405 around November 5–6, 2026, disabling version 4 transactions and permanently retiring its original Sprout privacy pool. The change leaves approximately 12,226 ZEC valued at $16 million unspendable even for users holding valid private keys, though the tokens remain counted in total supply. NU7 also reduces block target times from 75 to 25 seconds, aiming to tighten security and speed up transaction confirmations.

Migration deadline and risks for Sprout holders

• ▪Zcash holders face an NU7 activation deadline around November 5-6, 2026, to move funds out of Sprout addresses beginning with 'zc' into supported wallets
• ▪Public blockchain records for Zcash's Sprout pool cannot identify individual owners or establish how much stranded ZEC belongs to lost private keys
• ▪Early Zcash users who shielded coins in Sprout years ago and have not checked old wallet records face the primary risk of losing spending access under Zcash's NU7 upgrade

NU7 technical specifications for Sprout deprecation

• ▪ZIP 2003 defines Zcash's NU7 upgrade specification that rejects version 4 transactions, leaving open the possibility of restoring access to Zcash's Sprout privacy pool in a future upgrade while warning spending may never resume
• ▪Zcash developers scheduled the NU7 upgrade to eliminate Sprout's older transaction format to reduce software complexity and security risks in payment-verification code
• ▪ZIP 2003 states that the Zcash NU7 network upgrade at block height 3,543,405 will disable version 4 transactions, rendering unmigrated funds in the Sprout privacy pool unspendable

Sprout pool liquidity and withdrawals

• ▪Coins frozen in Zcash's Sprout pool after Zcash's NU7 activation could create a temporary market liquidity squeeze by effectively removing ZEC from active circulation
• ▪Only 40 ZEC was withdrawn from the Zcash Sprout privacy pool on Wednesday, November 4, 2026

Block time reduction and activation timing

• ▪The NU7 network upgrade cuts Zcash's target time between blocks from 75 seconds to 25 seconds, shortening expected wait times for transaction confirmations
• ▪Zcash block height stood at 3,542,391 at 05:24 UTC on November 5, 2026, leaving roughly 21 hours until Zcash's NU7 activation at the 75-second target block time

Zcash privacy pool modernization

• ▪Zcash steadily introduced the Sapling, Orchard, and Ironwood privacy pools after Sprout to modernize the network's protocol
• ▪The Zcash Sprout privacy pool, launched in October 2016 as the network's first shielded pool, has been restricted to withdrawals only for several years prior to NU7