Zcash activates NU7 network upgrade on testnet at block height 4,465,026

Zcash has switched on its NU7 network upgrade on the public testnet at block height 4,465,026. It is the first live environment where the privacy coin’s biggest protocol overhaul in years can actually be exercised.

The changes are substantial. NU7 aims to cut block times from 75 seconds to 25 seconds, introduce a fee-recycling system and retire one of Zcash’s oldest shielded transaction formats.

What NU7 actually changes

The upgrade ships through Zebra 7.0.0-rc.0, a release candidate of the Zebra node software released on October 2, 2026. Testnet activation was expected around October 6, 2026.

The headline feature is speed. ZIP 218 changes block spacing, bringing the target block time down to 25 seconds from the previous 75 seconds.

The second major piece is the Network Sustainability Mechanism, or NSM. Under the upgrade, the NSM directs 60% of transaction fees toward supporting the network’s longevity. Two proposals, ZIP 235 and ZIP 237, govern how the NSM functions.

The third change is a cleanup. NU7 retires the Sprout shielded pool, which disables v4 transactions. The upgrade also introduces no new transaction formats.

Testnet quirks and the road to mainnet

The testnet runs with a few parameters of its own. It features an adjusted third halving planned at block height 4,497,948, and NSM reissuance begins at block height 7,305,222.

The timeline from here is tentative. A mainnet decision is scheduled for October 20, 2026, with a target activation date of November 5, 2026.

Until then, mainnet operators do not need to do anything. No activation height has yet been designated for the mainnet environment.

Infrastructure providers are already moving. QuickNode was slated to finish the necessary testnet updates by October 5, part of broader preparations for node operator upgrades as the test phase advances.

Who agreed to this

Several organizations collaborated on the upgrade: the Zcash Foundation, Project Tachyon, Valar Group, ZODL and Shielded Labs. All of them reached a unanimous agreement on the upgrade’s scope after polling coinholders.

What this means for ZEC and its users

For traders, the clearest near-term signal is the calendar. October 20, 2026 is the decision date, and November 5, 2026 is the target for mainnet activation.

Exchanges, wallet providers and node operators are the stakeholders with the most homework. They have a narrow window between the October 20 decision and the November 5 target to confirm their systems are ready, assuming the schedule holds.

Retiring Sprout and disabling v4 transactions means any software still relying on those formats will need updating before mainnet activation.