What is Zcash Ironwood (NU6.3)?
Ironwood is Zcash's newest shielded pool, launched by the NU6.3 network upgrade at block 3,428,143 on 28 July 2026 after a flaw was found in the Orchard pool. New shielded funds now go to Ironwood, Orchard is withdraw-only through a public turnstile, and existing u1 addresses did not change.
Ironwood is the answer to the biggest scare in Zcash's history. After a bug was found in the Orchard pool in May 2026, developers decided not just to patch Orchard but to start a fresh shielded pool and move everyone into it through a checkpoint that lets anyone verify total supply. That pool is Ironwood.
Key facts
| Item | Detail |
|---|---|
| Upgrade name | NU6.3 (network upgrade 6.3) |
| Activation | Block 3,428,143, 28 July 2026 |
| Plan finalised | 9 June 2026 (The Block) |
| What it added | A new, formally verified shielded pool |
| What happened to Orchard | Closed to new value; funds can only leave, through a public turnstile |
| Addresses | Unchanged: existing u1 addresses keep working |
| Fees | Ironwood actions count like Orchard actions under ZIP-317 |
| Migration progress | About 88.2% of the Orchard balance had moved by 10 September 2026 (KuCoin) |
Why Ironwood was needed
On 29 May 2026 a security researcher found an under-constrained check in the Orchard circuit, present since Orchard launched in May 2022. In theory it could have let someone create ZEC inside Orchard without being detected, because shielded balances are encrypted. Orchard was frozen by an emergency soft fork on 2 June and fixed by the NU6.2 hard fork on 3 June 2026. No evidence of exploitation was reported.
A fix stops future abuse, but it cannot prove that no counterfeit coins were created in the past. The solution was to stop new deposits into Orchard, open a new pool, and make every coin leaving Orchard pass through a public checkpoint. Full story: the Orchard vulnerability explained.
How the turnstile works
Zcash nodes have always tracked the total value in each shielded pool, even though individual balances are hidden. The turnstile uses this: when funds leave Orchard, the amount becomes public, and the network will not let more leave Orchard than was ever put in. If anyone had secretly minted coins in Orchard, the pool would run dry before everyone could withdraw, and the shortfall would be visible. So far the migration has not reported such a gap; by 10 September 2026 about 88.2% of the Orchard balance had moved.
The trade-off is privacy during migration. Amounts leaving Orchard are visible, and your light-wallet server can see your IP address when you broadcast. That is why wallets spread migration across several smaller transactions and offer Tor.
What holders need to do
- Funds in Orchard: migrate them to Ironwood with an Ironwood-ready wallet. Zodl 3.9.0 (7 August 2026) added guided gradual migration; on Android it runs in the background, while on iOS you need to reopen the app. Step-by-step: Orchard to Ironwood guide.
- Funds in Sapling: Sapling was not affected and remains supported. You can leave them or move them to Ironwood.
- Transparent funds: shield them; Ironwood-ready wallets send newly shielded funds to Ironwood. Cake Wallet does this automatically.
- Using YWallet: it dropped Zcash support after NU6.3. Restore your seed in Zkool, the developer's successor. See YWallet to Zkool.
- Running zcashd: it reached end of life on 18 July 2026 and does not support Ironwood. Move to Zebra plus Zallet.
Which wallets are Ironwood-ready
| Status | Wallets (per ZecHub, October 2026) |
|---|---|
| Ready | Zodl, Zingo!, Zkool, Edge, Unstoppable, Cake Wallet, Keystone, Ledger (desktop, from 23 September 2026), Vizor, zecd, Zafu (beta), Zallet (beta) |
| In progress | Brave Wallet, KeepKey |
| Not ready | YWallet (retired), MetaMask Snap and other Sapling-only browser wallets |
| No shielded support | Trezor, Exodus, Trust Wallet, SafePal, Coinomi |
See our best Zcash wallets list and the full capability matrix.
Privacy tips for the migration
- Use your wallet's gradual migration rather than moving everything in one transaction.
- Turn on Tor in your wallet if available (Zodl and Zkool offer it; Zkool also supports Nym).
- Do not immediately deshield the same amounts you migrated.
- Ignore anyone who contacts you offering to "help migrate". No real wallet team will ask for your seed phrase. See Zcash scams.
After Ironwood: NU7
The next upgrade, NU7, was set for block 3,543,405, around 5 November 2026, with a delay still possible. It cuts the target block time from 75 to 25 seconds, disables v4 transactions and adds the Network Sustainability Mechanism. Developers said it introduces no new transaction formats and should not significantly affect wallets (Cointelegraph, 18 Sep 2026; KuCoin, 21 Oct 2026).
Frequently asked questions
Do I need a new Zcash address for Ironwood?
No. Ironwood uses the same receiver structure as Orchard, so your u1 unified address stays the same.
Is my Sapling ZEC affected?
No. The 2026 flaw was in Orchard only. Sapling remains a supported shielded pool.
What happens if I never migrate my Orchard funds?
Orchard is withdraw-only, so the funds stay spendable out of Orchard through the turnstile using an Ironwood-ready wallet. You cannot add new funds to Orchard.
Is the Ironwood migration private?
Partly. Amounts leaving Orchard are public by design, so supply can be audited. Spreading the migration over several transactions and using Tor reduces what can be linked to you.
Why is it called a turnstile?
Because every coin leaving Orchard has to pass a public counter, and the counter will not let more out than went in. That proves no hidden coins were minted.