TLDR
- Zcash activated NU7 at mainnet block 3,543,405 on November 6 at 02:34 UTC.
- The upgrade reduced target block spacing from 75 seconds to 25 seconds.
- Zcash reduced its per-block subsidy while preserving its existing issuance schedule and supply cap.
- The network now reserves 60% of transaction fees for future issuance, leaving miners with 40%.
- NU7 disabled version 4 transactions, making approximately 12,224 ZEC in Sprout unspendable.
- The upgrade increased theoretical Orchard transaction capacity while introducing limits to protect lightweight wallets.
Zcash activated its NU7 network upgrade on November 6, reducing target block intervals from 75 to 25 seconds. The upgrade went live at mainnet block 3,543,405, mined at 02:34 UTC. The activation introduced faster block targets alongside changes to mining rewards, transaction fees, and shielded transaction processing. It also disabled an older transaction format, leaving funds in Zcash’s original Sprout pool unspendable.
Zcash NU7 Cuts Target Block Time to 25 Seconds
According to Zcash Improvement Proposal 218, NU7 reduces the target waiting time for transaction confirmations by two-thirds. Under the previous rules, blocks arrived approximately every 75 seconds. The new target is 25 seconds, potentially reducing confirmation delays for exchanges, wallets, and payment services.
An exchange requiring three confirmations could see its expected waiting time fall from 225 seconds to 75 seconds. However, individual platforms determine their own confirmation requirements. The network initially operated above the new target. By 04:59 UTC, its first 225 post-activation blocks averaged approximately 39 seconds, according to ZecStats data.
Separately, CoinCentral examined ZEC trading activity and ETF flows surrounding the NU7 activation on November 6. Those market observations do not establish that the upgrade caused price changes.
NU7 also raises Orchard’s theoretical transaction capacity from about 2.9 to 6.6 transactions per second. The improvement comes alongside limits on shielded activity within individual blocks.
The Zcash Foundation estimates these limits reduce worst-case lightweight wallet synchronization bandwidth by approximately 37%. They restrict excessive shielded activity that could otherwise increase wallet processing requirements.
Zcash Adjusts Mining Rewards Without Increasing Supply
Under NU7, the scheduled block subsidy decreases from 1.5625 ZEC to approximately 0.52083333 ZEC. The reduction offsets the higher number of blocks produced under the new target interval. Consequently, planned daily issuance remains approximately unchanged.
This differs from NEAR Protocol’s recently approved issuance reduction proposal, which targets lower annual token creation over two years. Zcash also introduced a Network Sustainability Mechanism under ZIP 235. The mechanism removes 60% of transaction fees from circulation, while miners retain the remaining 40%.
Those withheld fees are not permanently burned. Instead, the protocol accounts for them as funds eligible for future issuance. Under ZIP 237, reissuance begins at mainnet block 8,939,664, expected around February 2031. The mechanism preserves Zcash’s four-year halving timetable and 21 million ZEC supply cap.
NU7 Disables Sprout Transactions and Freezes Legacy Funds
Another major change affects Sprout, Zcash’s original shielded transaction protocol. Under ZIP 2003, version 4 transactions became invalid when NU7 activated. This prevents transfers from the Sprout pool under the new consensus rules.
ZecStats recorded approximately 12,224.21 ZEC remaining in Sprout following activation. Those funds are currently unspendable but have not been permanently burned. The transaction restriction extends beyond Sprout. Other systems still creating version 4 transactions must migrate to supported formats.
Versions 5 and 6 remain valid. NU7 does not introduce an additional transaction format or shielded pool. No approved recovery mechanism currently allows holders to access the remaining Sprout funds.
Network Operators Must Run NU7-Compatible Software
The Zcash Foundation’s October 22 software release required mainnet node operators to upgrade to Zebra 7.0.0 before activation. Older versions cannot follow the upgraded consensus chain. The release also included seven security advisories and synchronization improvements.
Zcash’s rollout follows other recent blockchain infrastructure changes. A November 4 report on THORChain restoring Zcash swaps described a separate protocol update that restored trading across several networks. For Zcash infrastructure providers, NU7 changes consensus requirements immediately. Actual payment availability still depends on compatible software, network performance, and each service’s confirmation policies.
