Zcash NU7 upgrade goes live with 25-second block targets

The Zcash NU7 upgrade went live on mainnet on November 6, setting a 25-second target between blocks instead of 75 seconds. It also changes shielded activity limits and directs 60% of transaction fees to a reserve.

• NU7 activated at block 3,543,405, mined at 02:34 UTC on November 6, according to CoinDesk.
• The 25-second interval is a target, not a fixed confirmation time. CoinDesk reported that the first 225 blocks averaged about 39 seconds while mining difficulty adjusted.
• The Zcash Foundation says per-block rewards were divided by three, so faster blocks do not increase daily ZEC issuance.
• The Network Sustainability Mechanism directs 60% of each block’s fees to a reserve and leaves 40% with miners, according to the Foundation.
• NU7 invalidates version 4 transactions. Unchained Crypto reported that about 12,224 ZEC remaining in the Sprout pool became unspendable.

Timeline of the Zcash NU7 upgrade

1. September 2026: Nearly 2.4 million ZEC took part in a coinholder vote. Unchained Crypto reported that 99.9% of participating ZEC backed 25-second blocks, 98.9% supported retaining halvings, and 96.6% favored starting reserve reissuance in February 2031.
2. October 22, 2026: The Zcash Foundation announced Zebra 7.0.0, its first stable release with NU7 mainnet support. It told node operators to upgrade before block 3,543,405 to remain on the consensus chain.
3. November 6, 2026: NU7 activated at block 3,543,405, mined at 02:34 UTC. The Block reported that the upgrade went live, while CoinDesk recorded the activation time and early block intervals.

Background: what the Zcash NU7 upgrade changes

Zcash’s previous target spacing was 75 seconds. NU7 lowers it to 25 seconds, a threefold reduction. But early block production shows why the target is not a fixed confirmation time: CoinDesk said the first 225 blocks averaged roughly 39 seconds as difficulty adjusted.

The Foundation says faster blocks will not raise daily issuance. Each block’s reward is divided by three, while the 21 million ZEC supply cap and four-year halving schedule remain in place. More frequent blocks are offset by a smaller reward per block.

NU7 also sets limits on shielded activity. The Foundation estimates these raise Orchard throughput from about 2.9 to 6.6 transactions per second and cut worst-case bandwidth use for light-wallet syncing during spam by about 37%. These are estimates, not guarantees of performance in every network condition.

The Network Sustainability Mechanism, or NSM, directs 60% of each block’s transaction fees into a reserve, with miners retaining 40%. The Foundation places the first planned reserve reissuance at block 8,939,664, around 2031.

The upgrade ends support for version 4 transactions. Sprout transfers can only use that version, and Unchained Crypto reported that roughly 12,224 ZEC left in the Sprout pool at activation became unspendable. This affects those funds directly, rather than only changing future transactions.

Reactions and market context

The coinholder vote showed strong support among participating ZEC for 25-second targets and keeping halvings. It did not resolve every design preference. Unchained Crypto reported that Shielded Labs’ Jason McGee said the organization respected the result, although it had favored its original design.

The supplied market data has no ZEC price snapshot, so the immediate price response to activation cannot be established here. Bitcoin and Ether were lower on November 6: CoinGecko data at 08:13 UTC put Bitcoin at $75,514, down 6.29% over 24 hours, and Ether at $2,224.19, down 8.23%. Alternative.me’s Crypto Fear & Greed Index was 28, classified as Fear. These figures provide context, not evidence that NU7 caused market moves.

Outlook: what to watch after NU7

One question is whether block intervals move closer to the 25-second target as mining difficulty responds. The roughly 39-second average across the first 225 blocks is an early snapshot, not proof of a lasting interval. Node operators also need to keep pace with the consensus rules. The Foundation’s pre-launch warning makes software compatibility a practical concern for operators.

Shielded throughput and light-wallet bandwidth will show whether the Foundation’s estimates hold under real use. Unchained Crypto reported that Sprout funds tied to invalid version 4 transactions became unspendable after activation. The NSM’s planned reissuance around 2031 is a longer-term milestone; its fee allocation and standard ZEC supply rules are in effect now.

NU7 combines faster target blocks with unchanged issuance policy, shielded-activity limits, and a new fee reserve. Its longer-term impact depends on network performance and how the reserve works over time, not activation alone.

FAQ

What does the Zcash NU7 upgrade change?

It reduces the target block interval from 75 seconds to 25, introduces the Network Sustainability Mechanism, sets limits on shielded activity, and makes version 4 transactions invalid.

Does NU7 mean Zcash blocks always arrive every 25 seconds?

No. Twenty-five seconds is the target. CoinDesk reported that the first 225 blocks averaged about 39 seconds while mining difficulty adjusted, so actual intervals can differ.

Does the Zcash NU7 upgrade increase the amount of ZEC issued each day?

The Zcash Foundation says it does not. Per-block rewards are divided by three, while the 21 million ZEC supply cap and four-year halving schedule remain unchanged.

Sources

• Zcash’s major network upgrade NU7 goes live on mainnet, cutting block time by threefold (The Block)
• Zcash’s landmark NU7 upgrade goes live, speeding up private payments (www.coindesk.com)
• Zebra 7.0.0 Release (zfnd.org)

This article is for informational purposes only and does not constitute financial or investment advice. Cryptocurrencies are highly volatile; always do your own research before investing.