Zcash’s NU7 upgrade has gone live, leaving approximately 12,224 ZEC, worth 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 stranded funds are now unspendable because the upgrade rejects version 4 transactions, the only format that supports spending Sprout funds. However, the specification leaves open the possibility that a future network upgrade could restore access to these funds, though it warns that this may never happen.
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. Additionally, it introduces a Network Sustainability Mechanism that will remove 60% of transaction fees from circulation starting around February 2031, with plans to reissue them through future mining rewards. The upgrade maintains Zcash’s 21 million ZEC supply cap and halving schedule while introducing limits on shielded activity to reduce wallet synchronization demands.