Zcash NU7 Testnet Launch Cuts Block Times to 25 Seconds

Zcash’s upcoming NU7 upgrade has taken a significant step forward with its activation on the network’s public testnet. The upgrade went live at block 4,465,026 on October 4, 2026, introducing key changes in a pre-mainnet environment. The most notable adjustment is the reduction of target block spacing from 75 seconds to 25 seconds, which aims to significantly reduce the average wait time for a first confirmation.

The testnet deployment serves as a critical rehearsal before a potential mainnet launch. Developers plan to evaluate its performance before making a final decision on a proposed November activation. The upgrade also includes software support requirements for node operators, with the Zcash Foundation releasing Zebra 7.0.0-rc.0 as the first release candidate to support NU7 on the public testnet.

Under ZIP 218, NU7 changes Zcash’s target block spacing to 25 seconds, intended to improve first-confirmation wait times without increasing the overall quantity of ZEC issued. The upgrade pairs the timing change with an adjustment to per-block subsidies, ensuring that Zcash’s existing issuance schedule and 21 million ZEC supply cap remain unchanged.

Additionally, NU7 disables version 4 transactions, which affects holders of funds in Zcash’s legacy Sprout pool. Funds remaining in Sprout will become unspendable after NU7 activates unless they are moved beforehand. The upgrade’s final activation date is targeted for November 5, 2026, but this remains conditional pending a review of testnet performance on October 20.