A current breaking-news update says Zcash’s NU7 upgrade activated at block 3,543,405 on Friday at 02:34 UTC, leaving about 12,224 ZEC in the legacy Sprout pool without a usable transfer route. The key rule behind the change is set out in ZIP 2003: version 4 transactions are disallowed, and Sprout funds rely on that format to move.

Why NU7 Made Sprout Funds Unspendable

The reported trigger was NU7’s activation at block 3,543,405. Release notes from the Zcash Foundation for Zebra 7.0.0 state that NU7 activates on mainnet at that height and that nodes needed to upgrade before reaching it to remain on the consensus chain.

The mechanism stems from ZIP 2003, which disallows version 4 transactions. This matters because ZIP 2003 also states that barring v4 transactions prevents any remaining Sprout notes from being spent unless a future consensus change restores a way to do so. Put simply, this is not merely a wallet-support problem. A holder may still have the keys, but the network no longer accepts the transaction format needed to spend those Sprout funds.

ZIP 2003 frames the change as part of a broader effort to remove outdated Sprout-related complexity and attack surface from the protocol and node software. The current Sprout lockout is therefore best understood as the direct consequence of a consensus-rule change, rather than coins disappearing from the ledger.

Are the 12,224 ZEC Gone for Good?

Not under the current NU7 rules. ZIP 2003 explicitly says it does not propose to unissue, burn, or otherwise make Sprout funds permanently unavailable. It leaves open the theoretical possibility of re-enabling v4 transactions or introducing another mechanism to recover those funds.

However, the same proposal cautions that the ability to spend Sprout funds may never be restored. The strongest supported description is therefore that the funds are currently unspendable, not destroyed. Any recovery would require another consensus change, and no confirmed follow-up recovery path has been established.

The roughly 12,224 ZEC figure should also be viewed as a balance snapshot around activation, rather than a protocol-fixed constant. CoinMarketCap Academy reported 12,224.21 ZEC in the Sprout pool at block 3,543,046, before the reported NU7 activation height. This helps explain why reports may show slightly different totals without affecting the underlying rule: the network froze whatever qualifying Sprout balance remained when the new transaction rule took effect.