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Altcoins · 2 min read

Zcash Formalizes NU7 Upgrade Deployment Proposal in ZIP 259

The proposal sets Mainnet activation at block 3,543,405, cuts block times to 25 seconds, removes 60% of transaction fees, and invalidates Sprout transfers.

Editorial oversight: Julian Mercer, Chief Editor
Neutral
$ZEC $1,309 −0.8% $BTC $75,877 −5.9%

At a glance Proposed

What happened
Dev Ojha of Valar Group published ZIP 259, formalizing the consensus deployment terms for Zcash's NU7 upgrade.
Why it matters
The upgrade cuts block times to 25 seconds, burns 60% of transaction fees, and permanently deprecates version 4 transactions, making Sprout funds unspendable.
Who is affected
Zcash node operators, miners, wallet developers, and holders of legacy Sprout shielded tokens.
What's next
Testnet activation at block 4,465,026, followed by Mainnet activation at block 3,543,405.
Primary source
github.com: zips/zips/zip-0259.md at main · zcash/zips

Key points

  • ZIP 259 defines Zcash NU7 deployment at Mainnet block 3,543,405 and Testnet block 4,465,026 1.
  • Block target spacing drops from 75 to 25 seconds, while 60% of transaction fees will be burned out of circulation 1.
  • Version 4 transactions are permanently disabled, rendering remaining legacy Sprout shielded funds unspendable 1.

Zcash developers have published the deployment specification for the upcoming Network Upgrade 7 (NU7) under ZIP 259, authored by Valar Group's Dev Ojha 1. The proposal confirms the technical roadmap for the major consensus transition, targeting activation on Testnet at block 4,465,026 and Mainnet at block 3,543,405 1. At the time of writing, $ZEC traded at $1,312 amid broader market declines, with $BTC changing hands at $76,113.

NU7 introduces fundamental consensus modifications, most notably cutting block target spacing from 75 seconds down to 25 seconds via ZIP 218 1. To counterbalance validation load and shielded synchronization overhead caused by faster block creation, the upgrade establishes per-pool and global shielded action limits 1. Financially, NU7 deploys ZIP 235 to pull 60% of transaction fees out of circulation and incorporates ZIP 237 for the Network Sustainability Mechanism (NSM) 1. NSM reissuance will trigger at Mainnet block 8,939,664, calculated following the third post-NU7 halving, while maintaining the protocol's fixed supply cap 1.

Deprecation of Version 4 Transactions and Sprout Funds

Unlike previous cycles, NU7 introduces no new transaction format to limit parser and wallet disruption, preserving existing version 5 and version 6 structures 1. However, ZIP 259 enforces ZIP 2003, invalidating version 4 transactions across the network upon activation 1. Because legacy Sprout shielded pool transfers can only be encoded via version 4 transactions, any remaining funds inside the Sprout pool will become permanently unspendable once NU7 activates 1. Wallets must halt constructing version 4 transactions, as re-signing invalid transactions will not restore their validity 1.

ZIP 259 also waives standard upgrade deprecation timelines, allowing operators of unsupported software to stay online and follow an obsolete fork 1. Nodes compatible with Mainnet NU7 must advertise protocol version 170190 or higher, with upgraded clients configured to gradually disconnect peers running deprecated versions as activation nears 1. The upgrade notably incorporates revisions to funding streams under ZIP 207, ZIP 214, and ZIP 2008, while excluding contentious alternative issuance mechanisms such as ZIP 233 and ZIP 234 1. Earlier reporting noted how teams have readied infrastructure, including when Gemini migrated Zcash infrastructure to Zakura node ahead of NU7.

Questions this story raises

What happens to Zcash Sprout shielded funds after NU7 activates?
Because NU7 disallows version 4 transactions, and Sprout transfers can only be represented using that format, any funds remaining in the Sprout pool become unspendable after activation.
What software protocol version is required for NU7?
Nodes on Mainnet must run software that advertises network protocol version 170190 or higher to maintain consensus compatibility.

Sources

  1. [1] zips/zips/zip-0259.md at main · zcash/zips — github.com, November 6, 2026

Written by Basis Desk's newsroom system from the primary sources above and machine-verified against them before publication. Market figures marked "at the time of writing" come from live exchange data. Report an error: corrections@basisdesk.news · corrections policy.

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