Legacy Sprout Pool Locks 12,224 ZEC as Zcash Implements NU7 Network Update
The implementation of Zcash's NU7 network update has left approximately $15 million worth of legacy Sprout pool funds inaccessible, though future updates may provide a recovery mechanism.
The NU7 network update for Zcash went into effect on Friday, resulting in approximately $15 million worth of ZEC tokens becoming inaccessible within the network's original Sprout shielded pool infrastructure.
The implementation became active at block height 3,543,405 at 02:34 UTC, as reported by ZecStats blockchain monitoring service, which indicates the Sprout pool currently contains approximately 12,224 ZEC.
The network update reduces Zcash's designated interval between blocks from 75 seconds down to 25 seconds, though the real-world block generation intervals will gradually transition toward this new target as the mining difficulty undergoes adjustments.
According to Zcash Improvement Proposal (ZIP) 2003, the NU7 update blocks version 4 transactions, which represent the sole transaction format capable of facilitating Sprout fund transfers. The coins that remain in the pool are now unable to be moved under the updated protocol rules, though they have not undergone a burn process.
The technical specification maintains the option that a subsequent network update might potentially reinstate access, either through the re-activation of version 4 transaction capabilities or through the implementation of an alternative method for fund recovery. That said, it cautions that "the ability to spend Sprout funds may never be re-enabled."
The NU7 update additionally implements a Network Sustainability Mechanism that withdraws 60% of transaction fees from active circulation, designating them for eventual redistribution through future mining rewards, with this process scheduled to commence around February 2031.
The network update maintains Zcash's maximum supply ceiling of 21 million ZEC and its established halving schedule, while simultaneously implementing restrictions on shielded transaction activity aimed at decreasing the computational requirements for wallet synchronization processes.