Zebra 7.0.0 Brings NU7 Support to Zcash Mainnet

The Zcash Foundation has released Zebra 7.0.0, the first stable version of its Rust-based full node with support for the upcoming NU7 mainnet upgrade. NU7 is scheduled to activate at block height 3,543,405, expected around November 5, making the new release a required migration for operators that intend to remain on the upgraded consensus chain.

According to the Zcash Foundation’s official release announcement, Zebra 7.0.0 adds mainnet support for 25-second blocks, the Network Sustainability Mechanism and new limits on shielded activity. The release also improves synchronization near the chain tip and resolves seven security advisories identified during development and testing.

The stable release follows an October testnet cycle that exposed several synchronization issues before mainnet readiness. Moving from release candidate to stable software establishes client support for NU7, but the consensus changes themselves will not become active until the network reaches the designated block height.

NU7 Cuts Block Times and Changes Fee Economics

NU7 reduces Zcash’s target block spacing from 75 seconds to 25 seconds under ZIP 218. The threefold increase in block frequency is designed to reduce the average wait for a first confirmation from roughly 75 seconds to around 25 seconds, while requiring nodes and infrastructure providers to process substantially more blocks over the same period.

The faster schedule does not triple ZEC issuance. Block subsidies are divided by three and the remaining halving intervals are extended accordingly, preserving the existing issuance cadence over time and maintaining the 21 million ZEC supply cap.

NU7 also introduces a Network Sustainability Mechanism composed of separate consensus changes. ZIP 235 removes 60% of transaction fees from circulation, while ZIP 237 creates an algorithmic mechanism for previously removed or unclaimed value to be reissued through future block subsidies, rather than permanently destroying that value.

The distinction matters because the mechanism is not equivalent to Ethereum-style permanent fee burning. ZEC entering the NSM balance is temporarily outside circulating supply but remains eligible for future algorithmic reissuance, with the system designed to preserve the overall monetary cap.

Shielded transaction limits form another part of the upgrade. NU7 places per-block limits on Orchard, Ironwood and Sapling actions to constrain validation and wallet synchronization costs as block production becomes three times more frequent.

The higher block frequency has already influenced infrastructure decisions across the ecosystem. Gemini recently moved its Zcash backend from Zebra to Zakura ahead of NU7, highlighting how exchanges and infrastructure operators are evaluating synchronization and recovery performance before the new workload reaches mainnet.

Zebra 7 Changes Operator State and Compatibility

Zebra 7.0.0 also upgrades its state database format from v28 to v29. The first startup automatically moves compatible v28 state into the new format without requiring operators to download the blockchain again, reducing migration downtime for existing nodes.

The change is not reversible with the same database. Zebra 6.x cannot read v29 state, so an operator who upgrades and later wants to return to a 6.x release must either restore a preserved v28 backup or perform a new synchronization.

This continues a series of operational changes introduced throughout 2026. Zebra 5.2.0 previously expanded its local rollback window from 99 to 1,000 blocks, while earlier migration work around Zebra, Zakura and NU6.3 prepared infrastructure teams for a multi-client environment after zcashd’s retirement. The broader trend is toward more resilient and diversified node infrastructure rather than dependence on a single implementation.

The NU7 activation therefore represents both a protocol change and an operational deadline. Mainnet nodes running incompatible software will stop following the canonical NU7 chain once height 3,543,405 is reached, making client readiness more consequential than simply installing a routine maintenance release.

Zebra 7.0.0 provides the stable software needed for that transition, but the final test will occur only after mainnet activation. The upgrade’s practical success will depend on compatible nodes maintaining synchronization under 25-second blocks while the new fee, subsidy and shielded-action rules operate under production conditions.