The crypto community is currently counting down as Zcash is expected to activate its Ironwood network upgrade at block height 3,428,143 on July 28.
In a recent X post, the Zcash Open Development Lab (ZODL) shared a countdown to the Ironwood upgrade. In a post on July 26, ZODL wrote, “T-2 days until Ironwood is live on mainnet. Privacy shouldn’t require sacrificing verifiability. Ironwood ensures both.”
Zcash to Activate Ironwood Upgrade With New Shielded Pool and Supply Safeguards
Zcash is expected to activate its Ironwood network upgrade at block height 3,428,143 on July 28. The upgrade introduces a new shielded pool with quantum-recoverable notes and a turnstile mechanism… pic.twitter.com/CuFQ0RMAmt
— Wu Blockchain (@WuBlockchain) July 27, 2026
Ironwood is a Zcash network upgrade intended to make it possible for every user to independently verify the soundness of Zcash’s circulating supply. It is scheduled to activate as NU6.3 at block height 3,428,143, at about 12:00 p.m. UTC on July 28.
Ironwood was designed in response to a critical counterfeiting vulnerability discovered by Shielded Labs security researcher Taylor Hornby in Zcash’s Orchard shielded pool. The vulnerability was fixed through an emergency network upgrade led by the Zcash Open Development Lab (ZODL), which believes it was unlikely to have been exploited.
Given that Orchard’s transaction data is shielded, users cannot independently verify that no counterfeit $ZEC was created before the vulnerability was fixed. Ironwood addresses this problem by creating a new shielded pool using the corrected Orchard circuit and sealing the original Orchard pool.
Following the Ironwood upgrade, users will no longer be able to send or receive $ZEC inside the Orchard pool. Funds will only be able to leave through Zcash’s existing turnstile, which prevents more $ZEC from exiting the pool than legitimately entered it.
Why Ironwood matters
Ironwood retires the Orchard pool and seals the original pool, replacing it with a new pool using the corrected Orchard circuit.
The upgrade also prevents hypothetical counterfeit value from increasing Zcash’s circulating supply. Following the Ironwood upgrade, funds can only exit the original pool through the turnstile.
Ironwood also provides independently verifiable soundness whereby anyone running a node can verify that Zcash’s supply limits are being enforced.
Temporary service interruptions may be possible during the Ironwood upgrade, as exchanges, wallets, or other service providers that are not fully prepared for the transition may temporarily suspend deposits, withdrawals, or other services.
