Approximately 12,224 ZEC worth between $15 million and $16 million risks being permanently locked on the Zcash network once block 3,543,405 is reached on Thursday evening US time. ZecStats data indicates that the assets remain lodged in Sprout, Zcash’s original privacy pool active since its 2016 launch.
At the time of publication, the chain was at block 3,543,027. The consensus change via the NU7 upgrade is not merely routine maintenance, but a permanent shutdown of withdrawal pathways for first-generation wallets.
Why Funds in the Sprout Pool Could Be Locked
The NU7 upgrade permanently disables version 4 (v4) transaction formats. The v4 format is the only mechanism that can execute fund transfers out of the Sprout pool into newer pools. Without v4 transactions available, all coins remaining in Sprout lose any technical avenue to be transferred out or spent.
Network technical specifications confirm that the funds left in Sprout are neither destroyed nor burned. The 12,224 ZEC will continue to be counted as part of Zcash’s circulating supply. However, their status transitions to unspendable, with spending options confirmed to most likely never be re-enabled.
The “zc” Address Cutoff and Modern Wallet Checks
The obligation to migrate funds falls squarely on holders with balances at addresses starting with “zc”, the distinct identifier for Sprout pool addresses. Asset holders with those addresses must transfer their ZEC to a newer pool before validators process block 3,543,405. Users who miss this block deadline will permanently lose access to their funds.
The good news is that ZEC holders using modern wallets are in the clear. The NU7 consensus update does not affect users holding balances in the Sapling, Orchard, or Ironwood pools. Current modern wallets already operate on these newer-generation pools, so active ZEC holders do not need to take any technical action.
Closing Legacy Flaws and Slashing Block Times
The move to disable Sprout was decided in order to reduce network computational overhead while closing potential security vulnerabilities from legacy transaction verification systems. Supporting an outdated cryptographic system dating back to 2016 was deemed a burden on node operational efficiency, leading to the deprecation of the obsolete verification system.
Alongside the closure of Sprout, the NU7 upgrade brings performance improvements to network speed. Zcash’s target block interval is being reduced from 75 seconds to 25 seconds. The Zcash Foundation stated that this duration reduction speeds up transaction confirmations by up to three times for all network users.
For anyone still holding ZEC in legacy addresses starting with “zc”, only a few hundred blocks remain to secure the assets before Thursday evening US time. Past that point, while your coins will still be recorded on the ledger, the ability to move them will be lost forever.
Reported by Decrypt.
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Disclaimer: This article is for informational and educational purposes only, not financial advice. Cryptocurrency assets are highly volatile and carry significant risk. Always do your own research (DYOR) and never invest more than you can afford to lose.
