Zcash activated its NU7 network upgrade at block 3,543,405 at 02:34 UTC on Friday, moving the privacy-focused blockchain to a 25-second target between blocks. The upgrade also changes how transaction fees support future mining, places limits on shielded activity per block and disables the legacy transaction format used by the Sprout privacy pool. ZecStats showed hundreds of blocks built after the activation height by the time of verification, confirming that the upgraded chain had continued beyond the transition.

A faster target does not mean every block arrives in 25 seconds

NU7 reduces Zcash's target block spacing from 75 seconds to 25 seconds. The per-block subsidy falls to one third of its previous level, so the network still targets the same daily ZEC issuance and retains its 21 million coin cap. Early block intervals should not be read as a final performance benchmark: mining difficulty adjusts over time, and ZecStats said the post-upgrade pace was still moving toward the new target. Wallets and exchanges may also require different numbers of confirmations before making funds available.

Related reporting: Zcash targets November NU7 upgrade with 25-second blocks

Shielded capacity rises while wallet workload is bounded

The Zcash Foundation says new action limits apply to Orchard, Ironwood and Sapling shielded activity. Those limits are designed to prevent a single block from imposing unbounded synchronization work on light wallets while allowing the faster block schedule to raise capacity. Foundation estimates put the ceiling for simple Orchard payments at about 6.6 transactions per second, up from 2.9, while reducing worst-case synchronization bandwidth from spam by about 37%. Those figures describe protocol limits, not a guarantee of real-world throughput or user demand.

Sprout funds are frozen, not destroyed

NU7 makes version 4 transactions invalid. Because Sprout transfers depend on that transaction format, ZEC left in the oldest shielded pool can no longer be spent. ZecStats measured about 12,224.21 ZEC remaining there at activation. Calling those coins burned would be inaccurate: the balances still exist in chain history, but current consensus rules provide no valid way to move them. No approved recovery mechanism was identified in the deployment specification.

Fees now feed a future mining reserve

The Network Sustainability Mechanism removes 60% of each block's transaction fees from circulation into a transparent consensus balance, while miners retain 40%. The reserved amount is not permanently destroyed. ZIP 259 schedules gradual reissuance from block 8,939,664, estimated around 2031, to supplement future mining rewards. The Foundation says this design preserves the halving path and supply cap, but its practical security contribution will depend on transaction volume and fee generation over several years.

Operators and users still face compatibility checks

Node operators had to move to NU7-compatible software before activation or risk following an older consensus branch. Wallet providers, exchanges, mining pools and custodians must also decide when their integrations have accumulated enough post-upgrade evidence to resume normal handling. Users should therefore treat the network's successful activation separately from service availability at a particular platform. A working mainnet does not guarantee that every venue has completed its own software update, deposit checks or confirmation-policy changes.

What comes next

The immediate test is whether block production settles near the 25-second target without creating reliability or synchronization problems. Observers can compare chain-tip growth, orphaned blocks, wallet performance and exchange support as difficulty adjusts. NU7 delivers the features that earlier governance polls endorsed, but activation is the start of operational measurement rather than proof that every expected benefit has been realized.

Sources

AI-generated editorial image; not a photograph of the reported event. Prepared with AI assistance and source verification.