Zcash Activates NU7, Leaves 12,224 Units in Sprout Pool Unspendable

Key Facts

The Zcash network activated the NU7 upgrade on its mainnet on November 6 at block 3,543,405, at 02:34 UTC, according to CoinDesk Research. The chain continued without a fork after activation, indicating that the network passed the operational transition without splitting the ledger. The upgrade combines a shorter block production time with changes to fee distribution and shielded activity limits. A total of 12,224 ZEC in the legacy Sprout private pool remained unspendable after the new rules took effect. CoinDesk Research estimated the balance was worth about $15 million at activation.

The change aims to speed up transaction confirmations by cutting block time to one-third of its previous level, according to CoinDesk’s report on the upgrade. But the actual pace in the first hours remained slower than the new target: the network produced 225 blocks after activation through 04:59 UTC, with an average interval of about 39 seconds. The report attributed this to mining difficulty still adjusting to the new target. The initial improvement therefore came gradually as the network adjusted, rather than immediately at activation. The gap between the target time and the early average block interval reflects a transition phase immediately following the upgrade.

Among the technical changes intended to support usability, NU7 set limits on shielded activity to reduce the data download burden on light wallets. The specifications estimate that the maximum daily download falls from 271 megabytes before the upgrade to 169 megabytes afterward. Simple private transfer capacity could also rise from about 3 transactions per second to more than 6, according to CoinDesk estimates. These figures link the shorter block time to the network’s ability to process private payments at a higher rate while easing synchronization requirements for wallets. They are estimates of transaction capacity and technical burden in the upgrade specifications, while early measurements showed mining difficulty was still adjusting.

NU7 also resets the reward for each block to one-third of its previous level, while extending the halving schedule from once every 1,680,000 blocks to once every 5,040,000 blocks. CoinDesk Research said the change keeps issuance on a schedule of a halving about every four years, despite the change in block cadence. The update does not raise the fixed supply cap of 21 million ZEC. The network thus preserves its issuance path and specified supply cap while changing the reward size per block, according to the report. These adjustments place the issuance changes alongside fee changes in the upgrade’s structure.

On funding, NU7 allocates 60% of total transaction fees to a general reserve that will fund future mining rewards, according to CoinDesk Research. The mechanism starts with a balance of about 369 ZEC, but payouts will not begin at launch. The report set block 8,939,664 as the start of payouts, estimating it would be reached around February 2031. That means the allocated fees will accumulate in the mechanism before being converted into rewards for miners. The arrangement is part of the upgrade’s changes to fee routing and future mining rewards.

The balance locked in Sprout fell from 22,263 ZEC on October 31 to 12,224 ZEC when NU7 activated, after declining by about 10,000 ZEC in the final five days before the upgrade. CoinDesk reported on November 5 that the balance stood at about 12,226 ZEC that morning, compared with about 22,263 a week earlier. Most of the decline came on Sunday, when about 9,094 ZEC left the pool, followed by another 40 ZEC on Wednesday. According to the report, version-four transactions became invalid at activation; because Sprout transfers use only that version, the remaining balance could not be spent under NU7 rules. The coins were not burned, according to the description by ZecStats cited by CoinDesk Research, but remained in the pool and could not be spent under the current rules.

A mechanism to recover the frozen coins had not been approved for activation when CoinDesk published its report on November 5. The report said co-founder Sean Bowe had proposed a recovery system, while the possibility remained that spending would not be re-enabled. On technical readiness, six of the eight software and service components tracked by CoinDesk Research had released upgrade-ready versions by activation. The two node teams released supporting versions on October 22, while no exchange or mining pool had publicly announced support deployment. These details show that the on-chain activation was not accompanied, according to the report’s monitoring, by a similar announcement from trading platforms or mining pools.

The shift coincided with continued growth in the total supply held in Zcash shielded pools during October, which rose by about 27,000 ZEC to 4.97 million. The Ironwood pool balance increased by about 122,000 ZEC that month, while the older pools lost about 95,000 ZEC, according to CoinDesk Research. The movement highlights the differing trajectories of newer and older pools in the month before NU7 activated. On price, ZEC recorded a daily close of $1,281.11 on November 5, the latest close available in EL7 data before the date of the article. The available data does not include a close for the activation date itself.