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Zcash’s NU7 network upgrade activated on Friday at block 3,543,405, at 02:34 UTC, cutting off the only transaction format that can move funds out of the network’s original Sprout shielded pool. According to Cointelegraph, blockchain tracker ZecStats lists about 12,224 ZEC still in Sprout, valued at roughly $15 million and now unusable.
The coins were not destroyed and no private keys were taken, per Crypto Briefing. They still count toward supply, but they cannot be transferred under the new rules.
Also read: Zcash Turns 10 as Grayscale Backs Its 20% Dev Fund
Key facts
- Under Zcash Improvement Proposal 2003, which Cointelegraph identified as the governing rule, NU7 rejects version 4 transactions, the sole format that supports spending Sprout funds.
- The upgrade also moves Zcash’s target block interval from 75 seconds to 25 seconds; real intervals will drift toward the new target as mining difficulty adjusts.
- NU7 adds a Network Sustainability Mechanism that removes 60% of transaction fees from circulation for reissuance through future mining rewards, beginning around February 2031.
- Crypto Briefing reported that Sprout held roughly 22,300 ZEC in mid-October, meaning holders withdrew close to half the balance before activation.
- The supply cap of 21 million ZEC and the halving schedule are unchanged, and limits on shielded activity are meant to reduce wallet synchronization demands.
Where the two reports diverge
The outlets differ on the size of the frozen stash. Cointelegraph, citing ZecStats, put the Sprout balance at about 12,224 ZEC and the value at about $15 million. Crypto Briefing cited approximately 12,226 ZEC and about $16 million, based on ZEC trading between roughly $1,300 and $1,320. Both descriptions trace to a snapshot of the pool around activation, so the gap is small in coin terms but visible in the dollar figure.
Crypto Briefing also gave background the other report did not: Sprout launched in 2016 and has been limited to withdrawals for several years, and only version 4 transactions are affected, leaving the newer Sapling, Orchard and Ironwood pools running unchanged.
Why it matters
Sprout was Zcash’s first privacy pool, and its retirement is the network’s most consequential step yet toward shedding legacy code. The people most exposed are probably not active traders but early users who shielded coins years ago and have not opened those wallets since, per Crypto Briefing. Coins that can never move cannot circulate, so a large stranded balance could tighten the pool of spendable ZEC even though total supply is unchanged.
The upgrade also changes how the chain funds itself. Diverting most transaction fees for later reissuance through mining rewards, alongside the shorter block interval, alters the network’s economics without touching the 21 million cap.
What to watch
The active question is whether any recovery path gets proposed. ZIP 2003 states that “the ability to spend Sprout funds may never be re-enabled.” Meanwhile, watch whether wallet providers make it easier for remaining holders to move funds into supported pools, and track the Sprout balance, last near 12,224 ZEC, on ZecStats.
Reported by Cointelegraph.
Sources: Cointelegraph, Crypto Briefing