NU7 has reached Zcash’s public testnet. Developers can now test shorter block intervals ahead of an October 20 decision on the mainnet activation height.
Zcash’s NU7 upgrade activated on public testnet at block 4,465,026 on October 4, bringing the target interval between blocks down from 75 seconds to 25. Mainnet is still a separate step: November 5 is the target, with developers due to decide the activation height and whether to proceed on October 20.
Public testnet arrives ahead of the estimate
Zakura’s NU7 dashboard marks public testnet as active. Its chain snapshot published on October 4 at 19:07 UTC shows that the activation height had been passed that day. The earlier staging network is marked as shut down, while mainnet carries an estimated date. Testing has moved from a preparatory environment onto the network that public-testnet participants can join.
The Zcash Foundation’s October 2 Zebra release announcement had estimated activation around October 6. The trigger, however, was a predetermined block height, rather than a calendar deadline. Testnet reached that height earlier than expected. The Foundation’s October 2 post below describes the preparations before activation.
View the Zcash Foundation’s October 2 NU7 announcement on X
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What changes with 25-second blocks?
The ZIP 218 specification aims to shorten the wait for an initial confirmation, particularly for small payments and services requiring only a few confirmations. Blocks are intended to arrive more frequently on average, rather than precisely every 25 seconds. How many confirmations an exchange requires before crediting a deposit remains a separate decision.
Block spacing is not transaction finality. A 25-second target on testnet does not mean every mainnet transfer is final within that time, or that every exchange has shortened its deposit wait.
More frequent blocks do not triple scheduled ZEC issuance. The reward per block is reduced to compensate, while the number of blocks between halvings is adjusted to preserve the roughly four-year timetable. NU7 also includes a mechanism that puts 60% of transaction fees into a reserve supporting future network security. Miners receive the remaining 40%.
New limits on shielded actions per block aim to keep verification work manageable with the shorter interval. The testnet phase gives node operators, miners, wallet developers and block explorers a shared environment in which to check the new rules.
The mainnet decision is due on October 20
According to the developer timeline, the October 20 decision will take account of experience on testnet before setting a mainnet activation height. November 5 should therefore be read as a target, rather than an unconditional deadline.
“no Mainnet activation height has been set”
Zebra 7.0.0-rc.0 is a release candidate, not a stable mainnet release. The Foundation is asking testnet operators to help check compatibility using the updated software; it has not yet required mainnet operators to upgrade.
