Historical report: originally published by Decrypt on November 6, 2026, at 03:46:03 UTC+8. The activation schedule and balances below reflect that reporting, not a current network-status check.
Zcash’s planned NU7 upgrade could leave approximately 12,224 ZEC in its oldest privacy pool inaccessible—even to holders who still have their private keys. According to ZecStats data updated Thursday in the original report, those holdings were worth roughly $15 million to $16 million at then-recent prices.
The change was scheduled for block 3,543,405, expected Thursday evening in the United States. Activation depended on block production rather than a fixed clock time. At publication, the latest available block cited by Decrypt was 3,543,027.
What changes for Sprout
Sprout was Zcash’s original privacy pool, introduced when the network launched in 2016. Zcash uses zero-knowledge proofs to verify transactions without revealing private details such as amounts and addresses. Later privacy systems named in the report include Sapling, Orchard and Ironwood.
Sprout had already been closed to new deposits for years, while withdrawals remained possible. NU7 would remove that remaining route by invalidating version-4 transactions, the only transaction format capable of moving coins out of Sprout, according to the network’s technical specification.
ZecStats described the result as “frozen, not burned.” The coins would still count toward Zcash’s circulating issuance calculations, but holders could no longer spend them under the new rules.
The stated rationale was to retire obsolete technology: Sprout’s original privacy system required substantial computing resources, and maintaining its older verification mechanisms added complexity and potential security risks.
Which holders were affected?
The exposure was specific to ZEC remaining in Sprout, not all Zcash holdings. The report identified these practical distinctions:
- Legacy Sprout holders: Funds needed to move through a compatible withdrawal mechanism before activation to avoid potentially indefinite loss of access. Sprout addresses begin with
zc, a useful clue when examining old wallet records. - Users of modern supported wallets: Regular ZEC holdings outside Sprout did not require this migration, although keeping wallet software updated remained important.
- Unidentified or inactive holders: The blockchain could not reveal who owned the remaining Sprout balance. It was therefore unclear how much belonged to active users and how much was already inaccessible because keys had been lost.
A future network upgrade could theoretically restore spending, but that was not guaranteed. The specification explicitly warned that spending might never be re-enabled, and Decrypt reported no indication that the team intended to restore it. Possessing a private key alone would not override the network’s transaction rules.
A separate change: shorter block intervals
NU7 was also set to reduce Zcash’s target block interval from 75 seconds to 25 seconds. According to the Zcash Foundation, that meant transactions should receive their first confirmation approximately three times faster.
For Sprout holders, however, the critical threshold in the original report was block 3,543,405: any funds left in the pool at activation would become unspendable under the new rules.