Not all ZEC will be frozen. The ones truly facing a deadline are the old coins still hidden in the first-generation privacy accounts of Zcash: balances will not disappear, but the only channel to move them may close in November.

Written by: Daii

Imagine a bank still acknowledges your deposits but announces that starting next month it will no longer accept the old withdrawal slips you have.

Your money is still recorded in the account. The signature is indeed yours. However, the bank only processes new forms, while your old account can only fill in the old forms. By that day, you are not "out of money," but you will no longer be able to submit a withdrawal that will be processed.

This is the matter being discussed regarding Zcash.

1. Let’s clarify: what are Zcash and ZEC

Zcash is a cryptocurrency network that launched in 2016, and ZEC is the unit of currency within this network. The relationship is similar to "Ethereum" and "ETH": the former represents the operating rules and ledger, while the latter is the asset that can be transferred in the ledger.

The biggest difference between Zcash and Bitcoin is that it allows two types of transfer methods.

One is called transparent transfers. Anyone can see how much was transferred from whom on the public ledger, making it quite similar to Bitcoin.

The other is called shielded transfers, or privacy transfers. The network can still confirm “the payer has money, there is no double spending, and the transactions can be reconciled,” but it does not have to disclose the payment address, receiving address, or amount. Here, "shielded" means not removing coins from the blockchain but hiding transaction details. (Zcash Official Guide, Zcash Official Zero-Knowledge Proof Explanation)

To distinctly record privacy coins generated by different technologies, Zcash places them into different "shielded pools." The pool is not an exchange's fund pool nor is it a place where everyone hands over money to a manager. It is more like an independent vault section in the same ledger: each generation of privacy technology has its own address, key, and withdrawal rules.

2. Sprout is the first-generation vault, v4 is the only withdrawal form it recognizes

Sprout is the first-generation privacy system Zcash used when it launched in 2016, and it is also the first shielded pool. "Sprout" is just a development code name, meaning "bud" in English. Later, Zcash launched a more efficient new generation of privacy systems, and Sprout became the old zone.

Although the old zone is no longer suitable for daily use, it may still contain ZEC that early users have not moved out. They are typically controlled by old addresses starting with zc....

Next up is v4, which is the most likely to confuse people.

v4 is not Zcash 4.0 and is not the fourth version of any wallet. It is referred to as the "fourth version of transaction format," which can be understood as a standard transfer form recognized by the network. The form specifies which fields need to be filled in for a transaction, how to sign it, and how to prove that the money can be spent.

Zcash later introduced new forms like v5 and v6, but Sprout has one critical limitation: to spend money from the Sprout old pool, only the old form v4 can be used. The new forms do not retain the withdrawal fields for Sprout. Therefore, merely keeping the key is not enough; one must also possess a v4 transaction that the network is willing to process. (ZIP 259, Zcash Protocol Explanation)

3. What did NU7 do, and why does it make old coins unspendable

NU7 stands for Network Upgrade 7, which can be understood in Chinese as "Zcash's seventh network rule upgrade." It is not a new product for users to pay for, nor is it just a wallet app update.

The blockchain is checked by many computers working together. Everyone must adhere to the same set of rules to identify which transactions are valid. A network upgrade is when these computers collectively start using a new set of rules from an agreed-upon block—understood as a new page in the ledger.

NU7 plans to disable v4 in the new rules. The so-called "disable" does not mean deleting files on users’ computers, but rather that nodes running the Zcash network will respond, upon receiving v4 transactions, "This form is no longer valid; I will not write it into the ledger." Cointelegraph reported this change on September 23; the corresponding ZIP 259—which is Zcash's protocol modification proposal—states that after NU7 is activated, v4 transactions will be deemed invalid. (Cointelegraph, ZIP 259)

The causal relationship can be condensed into four steps:

• ZEC in Sprout can only be moved using v4 transactions;
• NU7 is preparing to stop the network from accepting v4;
• v5, v6 cannot be used to fill in withdrawal applications for Sprout;
• Consequently, the ZEC that remains in Sprout after the upgrade may continue to show in the ledger, but cannot form a network-recognized spending transaction.

This does not mean coins are destroyed. The ledger does not erase the balance, and the user's old spending key may still be intact. The problem is that the key is still there, and the door is still on the ledger, but the network-recognized action to open the door has been canceled by the rules.

4. Who needs to worry, and who is not within the freezing scope

This change does not mean "everyone holding ZEC must sell or transfer before November." The vast majority of regular users are not in Sprout.

The high-priority examination is for those who used early Zcash desktop wallets between 2016 and 2018, especially those who needed to download and verify the entire ledger on their local machines and still retain old wallet files or zc... addresses.

wallet.dat is a local file that early desktop wallets used to save keys, which can be understood as a digital keychain. A long string starting with SK... could be a spending key for Sprout, equivalent to the real key that opens the old vault. An address can only tell others where to remit funds, while the spending key authorizes spending that money.

Not in the same freezing scope are primarily:

• ZEC in exchange accounts; exchanges manage the underlying addresses but should still pay attention to their announcements;
• Transparent addresses starting with t1... or t3..., where the ZEC is not in the Sprout privacy pool;
• Modern wallets using later generations of privacy addresses.

Also note that "wallets created in 2017" do not necessarily mean "Sprout wallets." An old wallet may only hold transparent ZEC, or it may contain both transparent coins and Sprout privacy coins. Therefore, community support posts suggest saving the original files first, then identifying what is inside, without panicking simply because the words "old wallet" appear. (Zcash Community Recovery Instructions)

5. Why does the network prefer to leave this cruel deadline

Since some may not be able to migrate in time, why not keep v4 indefinitely?

Because keeping an old withdrawal system is not just about leaving a few lines of code in the server. All computers verifying transactions must continue to understand it, test it, and guard against any undiscovered vulnerabilities within it. Sprout uses Zcash's earliest generation of privacy technology, which has higher computational costs and carries older proof systems and historical security assumptions.

For the entire network, if an old privacy system has a vulnerability that allows the creation of forged transactions, the harm may exceed the old pool's balance itself: the market might begin to doubt whether the total amount of ZEC is real, or whether the privacy proofs are reliable. Community discussions have estimated that the Sprout pool contains around 22,621 ZEC; the choice faced by maintainers is whether to continue bearing long-term systemic risks for a small amount of dormant assets or to set the final migration window. (Zcash Community Discussion)

NU7 is currently still a plan, not a freeze that has completed today. The official timeline states the goal: to first test run on the test network on October 6, 2026, make a final decision for the mainnet based on test results on October 20, and activate it on the official network on November 5. The test network can be understood as a rehearsal environment, while the mainnet is the official ledger where the real money resides. (NU7 Official Community Timeline)

6. Novices only need to follow these four steps

If you have never used Zcash between 2016 and 2018 and have no old wallets, old hard drives, or ZEC backups left by others, this matter likely does not concern you.

If it possibly concerns you, do not rush to download unknown tools, and do not upload files to so-called "recovery customer service." Handle this in the following order:

• Search: Check old computers, hard drives, USB drives, and paper records for wallet.dat, wallet export files, zc... addresses, or SK... keys;
• Backup: Make at least two copies first, operate on the copies, and do NOT use the only original for trial and error;
• Determine: Confirm if it is a Sprout privacy coin or a transparent coin not subject to this freeze;
• Transfer: Look for current migration tools from official Zcash or trusted community sources to transfer Sprout funds into a new wallet that is still supported; complicated recovery may take several hours or even days, so do not delay until the night before the deadline for upgrades.

Anyone who obtains a complete spending key, mnemonic phrase (a set of words that can restore the wallet), or wallet.dat can potentially transfer the money out. When seeking help, you can describe file names and address prefixes, but you must NEVER disclose complete secrets.

The most important takeaway for novices is not the terms NU7, v4, or Sprout.

But rather a more universal fact: blockchain records "which key the money belongs to," and network rules determine "what actions count as valid withdrawals." Only when both conditions are met can the assets on the ledger be truly usable assets.