Zcash NU7 Upgrade: Sprout Funds Frozen, Blocks Faster

Zcash's NU7 upgrade cut block times to 25 seconds, removes 60% of transaction fees from circulation, and locked roughly 12,224 ZEC in the legacy Sprout pool.

The Zcash NU7 upgrade has gone live on mainnet, and it changes two things at once: how fast the chain produces blocks and what happens to coins still sitting in the network's oldest privacy pool. With ZEC trading at $1,263.40 and down 4.12% over the past 24 hours, holders now have a concrete protocol event to weigh rather than a roadmap promise.

What happened in the Zcash NU7 upgrade

NU7 activated at block 3,543,405. According to the Zcash Foundation, the target interval between blocks falls from 75 seconds to 25 seconds, meaning transactions should receive their first confirmation roughly three times faster than before.

The upgrade also switches on the Network Sustainability Mechanism. Sources describe this part differently: The Block reports that 60% of each block's transaction fees are removed from circulation, while CoinDesk frames the same mechanism as fees set aside for future miners. Both descriptions point to the same design goal, but the exact accounting matters for anyone modeling long-term ZEC supply.

Alongside that, NU7 reduces the computational work wallets must do to locate private payments, and it makes version-4 transactions invalid. That last change is the one with the sharpest consequences.

Why the frozen Sprout balance matters

Sprout was Zcash's original privacy pool, introduced when the network launched in 2016. It has been closed to new deposits for years, but existing holders could still withdraw until now. With v4 transactions invalid, any ZEC left in Sprout can no longer be spent.

ZecStats data updated Thursday put roughly 12,224 ZEC in Sprout, which at recent market prices represented about $15 million to $16 million. A few points deserve emphasis:

The coins are frozen, not burned. They still count toward Zcash's circulating issuance calculations.
The blockchain cannot reveal who owns the remaining balance, so the mix of active users and lost keys is unknown.
A future network upgrade could theoretically restore access, but the technical specification warns that spending may never be re-enabled.

Sprout addresses begin with "zc", which gives holders a way to check whether old wallets are affected. Later privacy systems, including Sapling, Orchard, and Ironwood, are unaffected by this change.

Why it matters for ZEC holders and traders

For everyday users on modern, supported wallets, there is no migration to perform. The practical takeaway is to keep wallet software current, because NU7 reduces wallet-side work for finding private payments and older clients may not handle the new transaction rules cleanly.

For the network itself, retiring obsolete technology removes complexity and potential security vulnerabilities. Sprout's original privacy system demanded substantial computing resources, and its outdated transaction-verification mechanisms carry risks developers have wanted to eliminate. That is a genuine structural improvement, even if it does not show up immediately in price.

The coins are frozen, not burned. They still count toward Zcash's circulating issuance calculations.

Market reaction

ZEC is trading at $1,263.40, down 4.12% on the day, on 24-hour volume of $1,350,664,846 and a market cap of $21,509,913,122. A single down day tells us little about how the market is pricing NU7 specifically; the move could reflect broader conditions as easily as the upgrade itself.

One detail worth noting: the latest block reported at publication time was 3,543,027, still short of the 3,543,405 activation height. That is consistent with the fact that the exact activation moment depends on how quickly the chain produces blocks, not on a fixed clock time.

What to watch next

Three things are worth tracking from here. First, whether block production settles near the new 25-second target, since that affects confirmation expectations for anyone moving ZEC. Second, how the fee mechanism is ultimately accounted for, given the differing descriptions of whether 60% of fees are removed from circulation or reserved for future miners. Third, whether any proposal emerges to restore access to the frozen Sprout balance, which the specification explicitly does not guarantee.

For holders, the risk is less about immediate price action and more about understanding what changed. Coins in legacy pools are now out of reach; coins in supported modern wallets are not. That distinction is the real story of this upgrade.

FAQ

What is the Zcash NU7 upgrade?

NU7 is a Zcash network upgrade activated at block 3,543,405. It lowers the target block time from 75 seconds to 25 seconds, introduces a mechanism affecting transaction fees, and invalidates version-4 transactions.

Why did Zcash freeze the Sprout funds?

NU7 makes v4 transactions invalid, and Sprout relies on that older transaction format. As a result, roughly 12,224 ZEC remaining in Sprout can no longer be spent. The coins are frozen rather than destroyed and still count toward circulating issuance.

How does the fee mechanism affect ZEC supply?

The Network Sustainability Mechanism removes 60% of each block's transaction fees from circulation according to The Block, while CoinDesk describes those fees as set aside for future miners. Either way, the intent is to reduce sell pressure from fees over time.

Market snapshot

Prices at the time of writing (Nov 6, 2026 08:00 UTC).

ZCash (ZEC): $1,263.40 — 24h -4.12%

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Zcash NU7 Upgrade Freezes Sprout Funds and Speeds Blocks