Key facts
- Zcash's planned NU7 upgrade will disable version 4 transactions, making funds in the legacy Sprout shielded pool unspendable.
- Users holding ZEC in the Sprout pool must move their funds before the upgrade to avoid losing access.
- The NU7 upgrade is scheduled to activate on the mainnet on November 5.
- The upgrade will reduce Zcash's target block time from 75 seconds to 25 seconds.
Zcash users holding ZEC in the network's legacy Sprout shielded pool are being warned to move their funds before the planned NU7 upgrade on November 5, or risk them becoming unspendable. The upgrade, based on Zcash Improvement Proposal-2003, will disable older transaction formats that allow access to Sprout funds.
While the proposal will not burn the Sprout funds and leaves open the possibility of restoring access later, holders may never be able to spend funds left in the pool. A user on the Zcash Community Forum, posting as "vaspholdings," urged ZEC holders on Sunday to check old wallets, as only funds in the Sprout pool face the proposed restriction.
Zcash co-founder Zooko Wilcox also shared the warning on X. NU7 is scheduled to activate on testnet on October 6, with Zcash expected to decide on October 20 whether to proceed with the mainnet activation. The upgrade will also reduce Zcash's target block time from 75 seconds to 25 seconds, while preserving the network's halving schedule.