Zcash NU7 upgrade reported live on testnet, targeting 25-second blocks
In brief
- NU7 activated on Zcash's public testnet at block height 4,465,026, Crypto Briefing reported.
- ZIP 218 lowers the target block time to 25 seconds from 75 seconds.
- A new mechanism sends 60% of transaction fees toward the network's longevity.
- Sprout is retired and v4 transactions are disabled, so dependent software needs updating.
- A mainnet decision is set for October 20, with a tentative November 5 target.
What NU7 changes
Speed is the headline. ZIP 218 lowers the target block time to 25 seconds from the previous 75 seconds.
Fees get rerouted too. Under the upgrade, the Network Sustainability Mechanism (NSM) directs 60% of transaction fees toward supporting the network's longevity, and two proposals (ZIP 235 and ZIP 237) govern how it works. On testnet, NSM reissuance begins at block height 7,305,222, while an adjusted third halving is planned at block 4,497,948.
The third piece is a retirement. NU7 retires the Sprout shielded pool, which disables v4 transactions, and it doesn't introduce any new transaction formats, according to the report. That's the part developers can't ignore: any software still relying on Sprout or v4 will need updating before mainnet activation.
Timing and the road to mainnet
The upgrade ships through Zebra 7.0.0-rc.0, a release candidate of the Zebra node software released on October 2, 2026. Crypto Briefing's timeline isn't fully consistent, though. The same report that describes the activation also says testnet activation was expected around October 6, 2026.
Infrastructure providers are lining up behind it. QuickNode was slated to finish its testnet updates by October 5.
Mainnet is still a step away.
A mainnet decision is scheduled for October 20, 2026, with a tentative target activation date of November 5. Until then, mainnet operators don't need to do anything, and no mainnet activation height has been designated yet.
Who's behind the upgrade
The Zcash Foundation, Project Tachyon, Valar Group, ZODL and Shielded Labs collaborated on NU7. According to Crypto Briefing, the groups unanimously agreed on its scope after polling coinholders. The next checkpoint is the October 20 call.
Frequently asked questions
What does the Zcash NU7 upgrade change?
According to Crypto Briefing, NU7 aims to cut Zcash block times from 75 seconds to 25 seconds, introduce a fee-recycling system and retire the Sprout shielded pool. Retiring Sprout disables v4 transactions, and the upgrade introduces no new transaction formats.
How does the Network Sustainability Mechanism work under NU7?
Under NU7, the Network Sustainability Mechanism (NSM) directs 60% of transaction fees toward supporting the network's longevity. Two proposals, ZIP 235 and ZIP 237, govern how it functions. On testnet, NSM reissuance begins at block height 7,305,222.
When could NU7 reach Zcash mainnet?
A mainnet decision is scheduled for October 20, 2026, with a tentative target activation date of November 5, 2026, according to Crypto Briefing. No mainnet activation height has been designated yet, and mainnet operators don't need to take action until then.
