Zcash NU7 Activation Traps 12,224 ZEC Worth $15M in Sprout Pool

TL;DR

• Zcash Upgrade: NU7 activated at block 3,543,405, making roughly 12,224 ZEC in the legacy Sprout shielded pool unspendable under the network’s new transaction rules. The affected holdings are valued at around $15 million.
• Sprout Pool: The upgrade rejects version 4 transactions through ZIP 2003. Since those transactions were the only way to spend Sprout funds, the remaining coins cannot currently be transferred, though they have not been burned.
• Network Changes: NU7 also cuts the target block interval from 75 seconds to 25 seconds, introduces a mechanism that removes 60% of transaction fees for future reissuance, and preserves the network’s 21 million ZEC supply cap.
  

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A major network milestone has arrived for Zcash following the activation of the NU7 upgrade, a change that has effectively left around 12,224 ZEC in the blockchain’s legacy Sprout shielded pool unable to be spent under the network’s new rules. The upgrade went live at block 3,543,405 at 02:34 UTC, with the affected holdings valued at roughly $15 million based on current estimates. Although the coins remain recorded on-chain, the latest protocol changes prevent them from being transferred using the transaction format that previously supported Sprout funds.

NU7 has successfully activated on mainnet. A new era of Zcash is here. $ZEC pic.twitter.com/rPaSFe9h7j

— Zcash 🛡 (@Zcash) November 6, 2026

Why Zcash Sprout Funds Became Unspendable

For protocol users, the most significant consequence of NU7 is the treatment of remaining Sprout pool balances. According to the upgrade rules, version 4 transactions are now rejected under ZIP 2003. Under Zcash Improvement Proposal 2003, version 4 transactions were the only transaction format capable of spending assets held in the Sprout shielded pool.

As a result, the remaining coins can no longer be moved under current network conditions. The legacy Sprout holdings have not been burned or removed from the blockchain. Instead, they remain inaccessible because the mechanism required to spend them is no longer accepted by the network. The upgrade specification notes that future protocol changes could potentially restore access through a new retrieval method or by re-enabling version 4 transactions.

Zcash Reshapes Block Production

Beyond the Sprout changes, Zcash also introduced a new target block interval. The upgrade reduces the network’s target time between blocks from 75 seconds to 25 seconds. Although the new goal is already in place, actual block production is expected to move toward that target gradually as mining difficulty adjusts. The change is designed to alter the pace of block creation without affecting the network’s core supply parameters. The Zcash specification leaves open the possibility of recovering trapped Sprout funds in the future. However, it also cautions that spending access may never be restored, leaving the final outcome uncertain.

What Zcash Changes Mean for the Network

Zcash also introduces a Network Sustainability Mechanism that removes 60% of transaction fees from circulation for eventual reissuance through future mining rewards beginning around February 2031. At the same time, Zcash retains its 21 million ZEC supply cap and existing halving schedule. The upgrade further adds limits on shielded activity intended to reduce wallet synchronization requirements, marking one of the most notable protocol updates in Zcash history.