Zcash Upgrade Locks Sprout Coins Even With the Right Keys

The Zcash network’s NU7 upgrade will invalidate version-4 transactions at block 3,543,405, estimated near 02:30 UTC Friday, leaving about 12,226 ZEC in the Sprout shielded pool unable to move. The remaining Sprout balance was down from roughly 22,263 a week earlier. ZIP 2003 bars version-4 transactions from NU7 onward, and ZIP 259 sets the activation height. Sprout is affected because version-5 and version-6 transactions do not support it, leaving no supported replacement format. The Zcash Foundation’s Zebra 7.0.0 notice says nodes that do not upgrade may follow a different chain, and stranded Sprout balances remain part of Zcash’s issued supply.