Zcash NU7 testnet cuts target block time to 25 seconds

At block 4,465,026 on October 4 at 18:21:45 UTC, Zcash activated its NU7 upgrade on a public test network — ahead of schedule, according to CoinDesk. The headline change: target block time drops from 75 seconds to 25 seconds, a 66.67% reduction that puts blocks arriving three times as frequently. For users, that’s the part of NU7 most directly tied to confirmation waits and transaction throughput.

Cointelegraph confirmed the same block height and timestamp. The testnet is running NU7 rules through two implementations published in the days before activation — Zakura’s trial build, released October 1, and a test version of Zebra from the Zcash Foundation, released October 2.

The fee and reward changes running alongside the block-time cut are worth unpacking.

That’s calibrated to keep ZEC’s issuance schedule intact despite blocks arriving three times as fast. So what miners get under NU7 is more frequent block production, a lower per-block reward, and a 40% cut of fees.

Then there’s Sprout. NU7 disables transactions using the older Sprout privacy system entirely. CoinDesk reported that anyone with funds still sitting in Sprout needs to migrate them before mainnet activation or they’ll lose access through the existing system.

Developers are planning to review testnet results and make a mainnet call on October 20, with November 5 as the targeted activation date. What criteria would cause them to delay isn’t specified in available reporting, which means the public trial is doing real work right now — the block-time, fee-routing, reward reduction and Sprout retirement rules are all being assessed in a live environment before that decision lands.

November 5 is the date to watch.