Zcash NU7 Upgrade Could Freeze $16 Million in Sprout Funds

By Nathan Brooks

About $16 million in ZEC will become unspendable when Zcash activates the NU7 network upgrade around Nov. 5–6, 2026, at block height 3,543,405, according to the network’s upgrade schedule and the roughly 12,226 ZEC balance in the Sprout pool’s on-chain record.

NU7 will disable version 4 transactions, the only transaction type that can reach Sprout, Zcash’s original shielded pool. Any ZEC left in that pool after activation will remain counted in total supply, but holders will lose the supported path for transacting it. The protocol has no mechanism for recovering those funds after the upgrade.

Sprout launched in 2016 as a section of the Zcash ledger that keeps transaction details private. It now holds approximately 12,226 ZEC. At ZEC’s recent average price of $1,300 to $1,320, that balance represents about $16 million.

The distinction between ownership and spendability matters. NU7 does not burn the coins, and no authority is confiscating holders’ private keys. ZEC will remain in the network’s supply figures. Operationally, however, a post-upgrade attempt to transact funds remaining in Sprout will fail.

What does NU7 change for ZEC holders?

Holders with Sprout balances must move those funds into a supported wallet before block 3,543,405. Once NU7 activates, that migration route disappears. The deadline applies only to version 4 transactions and the Sprout pool. Zcash’s newer Sapling, Orchard and Ironwood shielded pools will continue operating normally, and NU7 will not touch them.

For several years, Sprout has operated on a withdrawal-only basis: funds could leave the pool but could not enter it. Zcash has since built newer privacy pools as part of a broader effort to modernize the protocol and tighten security. NU7 continues that development path by retiring the transaction format tied to the oldest pool.

The migration period is already reducing the balance at risk. Sprout held roughly 22,300 ZEC in mid-October, compared with approximately 12,226 ZEC now. That is a decline of a little under half in a short stretch. The figures indicate that holders are responding to the need to move funds before activation, although about 12,226 ZEC remain unmoved.

Early users are the group most exposed. These are likely people who shielded coins years ago and have not revisited their wallets, rather than active traders. For them, the issue is wallet access and transaction readiness, not market positioning. They need to confirm that their wallet supports the required transfer and complete it while version 4 transactions remain available.

That distinction also defines the practical market effect. Frozen Sprout coins remain visible in total supply but cannot circulate. If a meaningful share stays in the pool, the amount of liquid supply available to market participants could contract. The development could create a temporary liquidity squeeze that weighs on investor sentiment without specifying a price outcome.

Wallet providers could reduce execution risk before November by making migration easier for holders who have not used Sprout in years. A recovery proposal is another factor to monitor, but none exists today. Any future recovery route would require a protocol change; NU7 itself supplies none.

Three indicators matter as activation approaches: whether the Sprout balance continues to fall, whether wallets improve migration support, and whether any recovery mechanism is proposed. Until one of those changes occurs, the relevant risk remains operational rather than custodial. No one can spend the affected balance after the deadline under the rules scheduled for NU7.

The operative deadline is block 3,543,405: unless holders migrate the remaining Sprout balance or Zcash adopts a recovery mechanism, roughly 12,226 ZEC are likely to remain noncirculating indefinitely.