Zcash's NU7 upgrade reached its public testnet activation block on October 4, moving 25-second target blocks into a live network trial. Mainnet has not activated the upgrade, and its activation height remains unassigned.
ZIP 259, the deployment specification, sets the testnet threshold at block 4,465,026. ZecBlock records that block as part of the canonical testnet chain. Cointelegraph's October 5 report places its mining time at 18:21:45 UTC on October 4 and reports Zcash's confirmation of the activation.
The most visible change is a target block interval of 25 seconds instead of 75. That is a consensus target, not a promise that every payment settles in 25 seconds. Wallets, exchanges and bridges can retain their own confirmation requirements, and actual block production varies.
The Zcash Foundation's release announcement says the upgrade adjusts per-block rewards and halving intervals to preserve the scheduled rate of issuance. Faster blocks therefore do not mean three times as much new ZEC. Its Network Sustainability Mechanism allocates 60% of transaction fees to a reserve for future rewards, with miners retaining the other 40%.
Node operators have a concrete preparation task. Zebra 7.0.0-rc.0 supports the public testnet upgrade but is a release candidate. Its database migration uses format v29; the release notes tell operators to retain a v28 backup and upgrade direct database readers to compatible builds. Software support and a stable mainnet release are separate milestones.
NU7 also disables version 4 transactions. Cointelegraph reports that funds in the legacy Sprout shielded pool would become unspendable through the existing system unless moved before mainnet activation. The testnet change does not establish that this restriction already applies to mainnet holdings.
Developers plan to review test results and assign a mainnet activation height on October 20. November 5 is the reported rollout target, not a guaranteed launch. The immediate development is the public trial: operators can now test their infrastructure against the new consensus rules before a decision affecting real ZEC.