Zcash’s NU7 upgrade has gone live, leaving approximately 12,224 ZEC, valued at around $15 million, stranded in the legacy Sprout shielded pool. The upgrade activated at block 3,543,405 on Friday at 02:34 UTC, according to blockchain tracker ZecStats. The funds are now unspendable because the upgrade rejects version 4 transactions, the only format that previously allowed spending from the Sprout pool.
The NU7 upgrade also reduces Zcash’s target block time from 75 seconds to 25 seconds, though actual block intervals will adjust gradually as mining difficulty changes. While the stranded funds have not been burned, there is no guarantee they will ever be recoverable. The upgrade’s specification notes that access to these funds may never be re-enabled, though a future network upgrade could potentially restore them.
Additionally, NU7 introduces a Network Sustainability Mechanism that will remove 60% of transaction fees from circulation, with plans to reissue them through future mining rewards starting around February 2031. The upgrade maintains Zcash’s 21 million ZEC supply cap and halving schedule while implementing limits on shielded activity to reduce wallet synchronization demands.