Zcash Activates NU7 on Testnet, Cutting Target Block Times to 25 Seconds

Zcash’s NU7 upgrade activated on the network’s public testnet at block 4,465,026 on October 4, 2026, moving the planned protocol changes into a live pre-mainnet environment. The upgrade’s most visible change is a reduction in target block spacing from 75 seconds to 25 seconds, intended to cut the average wait for a first confirmation by threefold.

The public-testnet deployment is a rehearsal rather than a mainnet launch. Developers plan to assess its performance before making a final decision on whether to proceed with a proposed November activation.

NU7 reaches public testnet at block 4,465,026

The activation was reported by Unchained via Yahoo Finance as having taken place at testnet block 4,465,026. For node operators, the deployment required software support before that height rather than simply a change to a user-facing application.

The Zcash Foundation said its Zebra 7.0.0-rc.0 release was the first release candidate to support NU7 on public testnet, and instructed operators to upgrade ahead of activation. Release candidates are used to test software in conditions closer to a network rollout while remaining short of a production mainnet deployment.

That distinction matters in this case because NU7 combines a change to block timing with changes that affect transaction compatibility and the protocol’s issuance accounting. The testnet phase gives developers a defined period to review those changes together before selecting a mainnet activation height.

ZIP 218 cuts target block spacing to 25 seconds

Under ZIP 218, NU7 changes Zcash’s target block spacing from 75 seconds to 25 seconds. The upgrade specification says the objective is to reduce the average time users wait for a first confirmation by a factor of three.

The change is intended to improve first-confirmation wait times, not to increase the overall quantity of ZEC issued.

More frequent blocks without accelerating ZEC issuance

More frequent blocks would ordinarily raise a supply question: if per-block rewards stayed unchanged, a network producing blocks more often would distribute coins faster. NU7 is designed to avoid that outcome by pairing the timing change with an adjustment to per-block subsidies.

The Zcash Foundation said the subsidy adjustment accounts for the higher block frequency. According to the Foundation, it preserves Zcash’s existing issuance schedule and maintains the 21 million ZEC supply cap.

Together, the measures are intended to reduce the wait for first confirmations without accelerating issuance toward the fixed supply limit.

NU7 disables v4 transactions and sets a Sprout migration deadline

NU7 also carries a compatibility consequence for holders of funds in Zcash’s legacy Sprout pool. The upgrade disables version 4 transactions, according to the upgrade specification.

As a result, funds that remain in Sprout would become unspendable after NU7 activates unless they are moved beforehand. The deadline is tied to activation itself, making the issue separate from the faster block-time proposal and directly relevant to any remaining legacy-pool balances.

The specification states that v4 transactions are disabled as part of the upgrade, so the change does not depend on a future discretionary migration period after activation. Users and services with Sprout funds therefore face an operational requirement to move them before the final activation point.

October 20 review precedes targeted November 5 mainnet activation

Developers are targeting November 5, 2026 for NU7 mainnet activation, but that date remains conditional. A Zcash Community Forum timeline sets October 20 for a final go/no-go decision and selection of an activation height after developers review testnet performance.

The sequence leaves roughly a month between the public-testnet activation and the targeted mainnet date. During that interval, the network’s faster target spacing, revised subsidy calculation and transaction-version changes can be reviewed in the test environment before the mainnet height is set.

For now, November 5 is a target rather than a confirmed launch date. The October 20 review is the next stated decision point for determining whether NU7 proceeds to Zcash mainnet.

Disclaimer: This article is provided for informational purposes only. It is not offered or intended to be used as legal, tax, investment, financial, or other advice.