Zcash’s NU7 network upgrade is now running on the project’s public testnet, putting 25-second blocks into production on a test chain about a month before the change is due on mainnet.

The upgrade activated at block 4,465,026 on Oct. 4, according to a live NU7 dashboard run by the team behind Zakura, one of the two node programs that implement Zcash. The Zcash Foundation, which maintains the other, Zebra, had said in its release notes for the first NU7 release candidate that activation was expected around Oct. 6. Activation is tied to a block height rather than a calendar date.

As of early Monday UTC, the dashboard showed a median gap of 19.5 seconds across the latest 300 blocks. It lists a 17.3-second median as the expected figure when blocks average 25 seconds.

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Faster Payments, Same Issuance

NU7 cuts Zcash’s target time between blocks to 25 seconds from 75. “Today a Zcash user waits 75 seconds on average for a first confirmation. That is a real obstacle at a point of sale, for exchange deposits, and for cross chain bridges,” the foundation wrote.

Producing blocks three times as often does not mean three times the new supply. Each block’s scheduled reward is divided by three and the remaining halving intervals are lengthened to match, so the daily amount of new ZEC stays the same, the foundation said. The upgrade also sends 60% of every block’s transaction fees into a reserve for the Network Sustainability Mechanism, leaving miners with 40%. Coinholders voted in September to start paying that reserve back out through block rewards in February 2031.

NU7 also caps shielded activity in each block. Under those caps, Orchard’s throughput rises to more than twice its current level, and the most a spammer can slow down light-wallet syncing shrinks by roughly 37%, according to the foundation.

Mainnet Decision on Oct. 20

Valar Group and Project Tachyon, which build Zakura, set the testnet activation in version 1.6.0, released Oct. 1. The foundation released its Zebra candidate the next day.

Developers will decide on mainnet activation, and set its block height, on Oct. 20 based on how NU7 performs on testnet, according to a schedule posted by Zcash cofounder Sean Bowe, who co-maintains Zakura. Nov. 5 is the planned mainnet date. “The changes in this upgrade should not affect wallets in any significant way,” Bowe wrote in the forum post. “Infrastructure such as full nodes, indexers and block explorers may be affected.”

NU7 also turns off v4 transactions, suspending Sprout, Zcash’s original shielded pool. A forum participant replying in the same thread said funds left in Sprout after the upgrade would effectively be stuck.

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