Zcash Sets NU7 Upgrade for Block 3,543,405

Zcash developers have set the NU7 upgrade to activate at block 3,543,405, planned for around Nov. 5, according to the Zcash Foundation’s Zebra 7.0.0 release. It cuts target block spacing from 75 seconds to 25, which can shorten waits for payment confirmations.

The change is designed to make shielded Zcash payments confirm sooner without increasing the amount of ZEC issued each day. The activation height gives wallets, exchanges and node operators a specific point to prepare for.

For users, the main change is quicker expected confirmations; for node operators and some holders, NU7 requires action before it activates.

How much faster should payments confirm?

Under NU7, the average wait for a first confirmation is expected to fall from about 75 seconds to about 25 seconds, the Foundation says. A service that waits for three confirmations would see its target wait fall from 225 seconds to 75 if it keeps the same confirmation rule, according to CoinDesk’s report on the activation block.

These are targets, not guarantees: actual block times vary, and exchanges set their own deposit confirmation policies. The upgrade does not require a new transaction format, but services that rely on Zcash infrastructure may need compatible software to follow the upgraded chain.

What do node operators need to do?

Mainnet node operators need to upgrade before block 3,543,405 to remain on the consensus chain, the Foundation says. Its Zebra 7.0.0 release is the first stable Zebra version with NU7 mainnet support; after activation, nodes that have not upgraded will follow a different chain.

NU7 also changes how transaction fees are handled. Miners keep 40% of fees in each block, while 60% goes into a reserve for future mining rewards; the Foundation says the existing four-year halving schedule and 21 million ZEC supply cap remain unchanged.

Do holders need to move older Zcash funds?

Anyone with funds in Sprout, Zcash’s oldest shielded pool, should move them before activation if they want to keep spending them through the existing system. NU7 disables version 4 transactions, which Sprout transfers require, so funds left there become unspendable after the upgrade.

For other wallet users, the announced changes do not introduce a new transaction format. The immediate preparation is for infrastructure operators to update software and for Sprout holders to move funds before the planned activation.

Sources

• Zebra 7.0.0 release — forum.zcashcommunity.com
• CoinDesk’s report on the activation block — coindesk.com