Zcash NU7 activates on testnet with 25-second blocks, mainnet set for Nov 5

Zcash's NU7 network upgrade went live on public testnet at block 4,465,026 on October 4, two days ahead of its scheduled October 6 milestone and about a month before the planned November 5 mainnet activation. The upgrade cuts the target block time from 75 seconds to 25, redirects part of transaction fees to a mining-reward reserve, and permanently disables the legacy Sprout privacy pool.

What NU7 ships

Three changes land together, per CoinDesk's coverage of the testnet activation:

• Block spacing drops from 75s to 25s. Per-block subsidy is reduced to one-third to keep the total ZEC issuance schedule intact.
• Network Sustainability Mechanism (NSM): 60% of transaction fees are routed into a reserve that pays future mining rewards; the remaining 40% go to miners immediately.
• Sprout shielded pool is disabled. Any ZEC still in Sprout must migrate to Sapling or Orchard before mainnet activation or it becomes unspendable through the standard transfer path.

For users, the practical effect is a confirmation profile that collapses from roughly 225 seconds (three confirmations at 75s) to about 75 seconds — a factor-of-three improvement in payment finality for merchants and exchanges, as crypto.news summarised from the Zcash Foundation.

Client support

Both major Zcash node implementations ship NU7-compatible builds for the testnet trial. Zakura released its implementation on October 1; the Zcash Foundation published a test build of Zebra on October 2. Exchanges, wallets, and payment integrators are using the window between October 4 and November 5 to rehearse the shorter cadence against production tooling.

Timeline

• Oct 4 2026 — testnet activation at block 4,465,026.
• Oct 20 2026 — developer review of the testnet results; the final mainnet activation height is set here if go-ahead is given.
• Nov 5 2026 — scheduled mainnet activation.

What to watch

1. Sprout migration volume. Any ZEC still sitting in Sprout wallets after mainnet activation faces a hard cut-off. Expect wallet UX nudges in the next four weeks.
2. The Oct 20 developer decision. A delay here pushes mainnet past Nov 5; a clean sign-off locks the activation height.
3. Chain reorg and orphan behaviour at 25-second spacing. Shorter blocks mean more frequent natural orphans; mining pools and SPV wallets have different thresholds for how deep a confirmation needs to be before it is treated as final.
4. NSM reserve accrual. The 60% fee-to-reserve share creates a visible mining-subsidy buffer; its growth rate is a direct read on how much the network earns beyond issuance.

Context

NU7 is Zcash's seventh named network upgrade and the first since NU6 shipped the Zcash Shielded Assets groundwork. It is also the first Zcash upgrade whose headline feature is throughput rather than privacy architecture — the sustainability mechanism and faster blocks are a response to the longer-term question of what pays miners once block-reward emissions decline. Monero shipped its own 2-minute block target in 2016; Zcash is now the privacy chain with the fastest base-layer settlement cadence among coins that still support shielded transactions by default.