Zcash’s planned Sprout freeze would leave private keys unable to move funds

Zcash's proposed NU7 upgrade would close the spending route out of its oldest privacy pool, Sprout, which still held about 22,309 ZEC on Oct. 17. Holders could keep their private keys and still lose the ability to move those funds on the upgraded network.Mainnet activation remains undecided. The NU7 deployment specification leaves the activation height unassigned, with a final decision planned for Oct. 20 after testnet experience. Nov. 5 remains the target, conditional on that decision.The zkp.baby dashboard recorded 22,309.44195128 ZEC in Sprout at block 3,521,260, updated at 19:10:09 UTC on Oct. 17.The change is set out in ZIP 2003, a Zcash improvement proposal whose listed owner is Daira-Emma Hopwood. It proposes rejecting version 4 transactions from NU7 onward. Sprout transfers require that format; neither version 5 nor version 6 supports them.A private key authorizes a spend, but the network must also accept the transaction carrying it. Under the proposed rules, Sprout holders would have no supported format in which to exercise that authority.The restriction reaches every version 4 transaction, including transparent-only and Sapling transactions. The consequences differ by poo...