Zcash
The Zcash Foundation has released Zebra 7.0.0, introducing support for the NU7 network upgrade and requiring mainnet node operators to update their software before block height 3,543,405, expected around November 5. Operators who fail to upgrade risk losing synchronization with the network’s active consensus chain, while older Zebra 6.4.x releases are scheduled to shut down several days before activation.
The release marks a significant infrastructure change for Zcash, combining faster block production with adjustments to mining rewards, transaction-fee allocation and network resource management. The foundation also identified fixes for five security advisories among the release’s features.
The upgrade deadline is particularly important because incompatible nodes may continue operating without following the post-NU7 consensus rules. According to the network’s compatibility specification, upgraded nodes will disconnect peers advertising an older network protocol version after activation. Operators who remain on unsupported software could therefore follow a pre-NU7 consensus branch rather than the upgraded network.
The foundation’s engineering team has also scheduled the expiration of Zebra 6.4.x for around November 2, several days before the anticipated mainnet activation. The software’s operating period was shortened from 15 weeks to 12 weeks to ensure that older releases stop functioning ahead of the planned transition.
Developers have adjusted expiration calculations and synchronization estimates to account for the block time applicable at each height. This matters because NU7 reduces the target block interval from 75 seconds to 25 seconds. Without height-specific timing calculations, the change in block production could cause software to expire earlier than intended.
NU7 previously reached the public testnet at block 4,465,026 on October 4, allowing developers to observe the consensus changes before mainnet deployment. The mainnet activation height was selected following an October 20 meeting of ZIP editors, with block 3,543,405 subsequently listed in the deployment specification.
The central protocol change is defined in ZIP 218, which targets a reduction in block spacing from 75 seconds to 25 seconds. Shorter intervals could improve the speed at which payments, exchange deposits and cross-chain operations receive initial confirmations, reducing waiting times for applications that depend on Zcash transaction settlement.
However, faster block production does not automatically make transactions three times more secure or justify reducing confirmation requirements. ZIP 218 does not recommend that clients lower their confirmation counts. The security implications depend on factors including an attacker’s mining power and the economic cost of reversing a payment. Applications will therefore need to assess confirmation policies against their own risk models rather than treating the shorter interval as a direct replacement for existing security assumptions.
NU7 also preserves Zcash’s scheduled daily issuance despite the increase in block frequency. Under the revised reward calculations, scheduled block rewards are divided by three to account for the production of approximately three times as many blocks over a given period. The four-year halving schedule and the maximum supply of 21 million ZEC remain unchanged.
This distinction is important for assessing the upgrade’s potential tokenomics impact. Although more blocks will be produced each day, the scheduled mining subsidy is not expected to triple. The change primarily affects the timing and distribution of block production rather than the overall daily issuance schedule.
The proposed changes also received substantial support in a September coinholder poll. Approximately 99.9% of participating voting power supported shorter block intervals, while 98.9% favored preserving the existing halving schedule.
Nearly 2.4 million ZEC participated, representing around 66% of eligible Ironwood balances at the snapshot. A separate proposal to introduce a mechanism for redirecting transaction fees toward future mining rewards received approximately 96.6% support.
That mechanism, known as the Network Sustainability Mechanism, introduces another change to Zcash’s economic structure. Under the design described by the foundation, 60% of transaction fees are allocated to a reserve, while miners retain the remaining 40%. The reserved funds can then be gradually returned to circulation through future block rewards.
The deployment specification identifies block 8,939,664, expected around February 2031, as the point when reissuance is scheduled to begin. This is separate from NU7’s initial activation height. The mechanism therefore introduces a longer-term change to fee distribution without immediately altering the network’s scheduled daily issuance.
The revised fee structure also creates additional operational requirements for mining pools. The foundation’s technical explanation instructs miners to request fresh block templates rather than manually modifying the transaction set or previous-block reference in an existing template. This is intended to preserve the validity of coinbase transactions, which depend on the selected transaction fees and the reserve associated with the parent block.
NU7 also introduces limits on shielded activity to manage resource consumption as blocks become more frequent. ZIP 218 sets a shared shielded-activity budget of 330 actions per block, alongside separate limits for individual pools. The proposal estimates that these measures could reduce worst-case daily light-wallet synchronization bandwidth from 271 megabytes to 169 megabytes, a reduction of approximately 37%.
The bandwidth adjustment is relevant because shorter block intervals can increase the demands placed on wallets and network infrastructure. Controlling shielded activity could help prevent excessive synchronization requirements and reduce opportunities for spam, particularly for light-wallet users.
The design nevertheless retains a privacy-related trade-off. More frequent blocks provide observers with finer-grained transaction timing information that could be combined with data from networks or applications. The specification acknowledges that the new limits do not eliminate traffic-analysis risks or prevent denial-of-service attacks.
For the market, the immediate focus is operational rather than a direct change to ZEC’s issuance schedule. The approaching activation deadline creates a clear requirement for node operators, exchanges and other infrastructure providers to confirm compatibility with Zebra 7.0.0. A smooth transition would allow the network to adopt shorter block intervals and revised fee rules without the disruption associated with incompatible software.
The next milestones are the expected November 2 shutdown of Zebra 6.4.x and NU7 activation around November 5. Attention will then turn to whether the upgraded network operates as intended, how applications handle confirmation requirements under the shorter block interval, and whether the new shielded-activity limits deliver the projected efficiency gains. Longer term, the scheduled introduction of reserve reissuance around February 2031 will determine when the Network Sustainability Mechanism begins returning reserved fees through future mining rewards.
