Zcash Moves NU7 to Public Testnet

Zcash enabled NU7 on its public testnet at block 4,465,026, which was mined at 18:21:45 UTC on October 4. The activation occurred ahead of the previously estimated October 6 schedule. The Zcash Foundation confirmed the upgrade is now live for testing purposes on the network.

The move places the full protocol changes under real conditions. Developers and operators can now monitor performance before a final call on mainnet deployment. This step follows extensive preparation, including the release of Zebra 7.0.0-rc.0 on October 2 that added NU7 support to the testnet.

Core Protocol Changes Under Test

NU7 reduces the network’s target block spacing from 75 seconds to 25 seconds. The shorter interval aims to lower the average wait for the first confirmation from 75 seconds to 25 seconds and increase overall throughput as block production accelerates.

Shielded action limits were also introduced to manage the volume of shielded transactions that can be included in each block. These restrictions seek to prevent spam while block creation becomes more frequent.

The upgrade disables version 4 transactions on mainnet. Any ZEC remaining in the legacy Sprout shielded pool would become unspendable after activation unless holders migrate their funds in advance.

Network Sustainability Mechanism Added

NU7 incorporates a Network Sustainability Mechanism that redirects a portion of transaction fees into a reserve for future block rewards. The system recycles part of the fees to support ongoing network operations without changing the existing issuance schedule.

Miners receive 40 percent of each transaction fee, with the remaining 60 percent directed to the reserve. Per-block rewards adjust accordingly to maintain the original halving timeline. Private governance polls involving nearly 2.4 million ZEC showed strong support for both the block-time reduction and this funding approach, with more than 98.9 percent backing the continued halving schedule and approximately 96.6 percent endorsing the February 2031 start for reissuance.

Mainnet Decision Set for October 20

Developers plan to review the testnet results on October 20 before deciding whether to proceed with mainnet activation and setting the official activation height. Mainnet deployment remains targeted for November 5, though the exact date could shift based on observed performance.

Testnet operators were instructed to run the Zebra 7.0.0-rc.0 release candidate under live conditions. The phase provides several weeks for evaluation before any production network changes take effect.

Preparations for NU7 included prior work on Zebra versions and coordination with exchange infrastructure, such as Gemini’s move to a new backend that completed the chain tip in under six hours. The upgrade follows Zcash’s recent Ironwood activation in July, which addressed supply uncertainty in a prior shielded pool.

With testing now underway, the network continues to support privacy-focused features while advancing toward potential efficiency gains on mainnet.