Zcash NU7 Testnet Live with 25-Second Blocks Ahead of November Launch

Zcash has activated its NU7 network upgrade on the public testnet, introducing 25-second blocks ahead of the planned November 5 mainnet launch. The upgrade went live at block height 4,465,026 on October 4, slightly ahead of the October 6 estimate set by the Zcash Foundation.

The key change in NU7 is the block speed, reduced from 75 seconds to 25 seconds under ZIP 218. This threefold speedup aims to improve point-of-sale payments, exchange deposits, and cross-chain bridges. The daily issuance of ZEC remains unchanged, preserving the 21 million supply cap and four-year halving schedule.

NU7 also introduces a Network Sustainability Mechanism under ZIPs 235 and 237. This mechanism removes 60% of each block’s transaction fees into a reserve while miners keep 40%. A small, predictable slice of the reserve is reissued with each block to support network security post-halving. The reserve is seeded with the historical funding shortfall from before NU6.

The upgrade also tightens shielded transaction limits, increasing Orchard throughput and reducing the worst-case sync load on light wallets by about 37%. The testnet activation allows operators to upgrade and report issues before a mainnet decision on October 20. If successful, the mainnet activation is targeted for November 5.