Zcash NU7 Upgrade Freezes Sprout Coins: What ZEC Holders Need to Check Now
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Zcash’s NU7 network upgrade is due to activate at block 3,543,405, which CoinDesk estimated would arrive around 9:30 p.m. ET on Thursday, November 5, 2026 (about 02:30 UTC on Friday). Our own check of the chain on Thursday morning, at block 3,542,672 per Blockchair, pointed to the same window. Miners set the actual pace, so the time can shift.
Most coverage leads with faster blocks, but the part that can cost someone money is quieter: when NU7 goes live, coins still sitting in Sprout, Zcash’s original 2016 privacy pool, become unspendable, even for people who hold the correct keys. Roughly 12,226 ZEC, worth about $16 million at around $1,300 per coin, was still there on Thursday morning, according to ZecStats data cited by CoinDesk.
Most ZEC holders have nothing to do. This guide helps you work out whether you are the exception and covers what changes for everyone else.
What Is Zcash NU7?
NU7 is a scheduled hard fork. Developer Sean Bowe announced its scope and timeline in September, describing unanimous agreement among the teams involved. It makes three main changes:
- Faster blocks (ZIP 218): the target time between blocks falls from 75 seconds to 25 seconds. The per-block subsidy is divided by three and the halving interval is scaled up to match, so daily issuance and halving dates stay essentially where they were.
- Fee removal (ZIP 235 and ZIP 237): 60% of each block’s transaction fees is taken out of circulation and miners keep 40%. This is not a permanent burn. The removed ZEC is designed to be reissued through future block subsidies, starting in February 2031 under the setting coinholders chose.
- Version 4 transactions end (ZIP 2003): from activation, only version 5 and 6 transactions are valid. This is the change that freezes Sprout.
Cointelegraph reported that 99.9% of the ZEC-weighted vote backed the faster-block proposal and 98.9% supported keeping the existing halvings. Bowe also said NU7 brings no new transaction formats and should not significantly affect wallets, although full nodes, indexers and block explorers may need adjustments.
Why Sprout Coins Freeze
Sprout launched with the network in October 2016. It was later replaced by the Sapling pool in 2018, then Orchard in 2022, and most recently Ironwood, which became Zcash’s primary pool in July 2026 after a serious flaw was found in Orchard’s circuit. Sprout has been exit-only for years: funds can leave, but nothing new can enter.
The catch is technical. According to ZIP 2003, Sprout transfers can only be expressed in version 4 transactions, and the newer formats do not support them. Turn off v4 and there is no longer any valid way to spend a Sprout note. The ZIP justifies this by citing the pool’s minimal use and the denial-of-service concerns its old code adds to transaction handling.
The ZIP does not burn or unissue anything, and the coins still count toward issued supply. It also leaves open a theoretical path to re-enabling v4 or adding a retrieval mechanism, while warning plainly that Sprout spending may never return. Nobody should plan around a rescue.
Who Is Actually Affected?
You are very unlikely to be affected if your ZEC is on an exchange, was bought in recent years, or sits in a modern wallet. You should check if you ran an early Zcash wallet, especially around 2016 to 2018, and have not touched it since. The address prefix tells you where you stand:
- zc… is a Sprout address, and this is the one affected by the freeze.
- zs… is a Sapling address. It keeps working.
- u1… is a unified address, used for Orchard and Ironwood. It is not frozen by NU7, though Orchard itself is already withdraw-only.
- t1… and t3… are transparent addresses. They are not frozen.
There is a trap for anyone relying on a recovery phrase. Sprout keys were not derived from a seed, so a seed phrase on its own will not restore them. The wallet file is the real backup. That makes an old wallet.dat on a forgotten laptop or drive the thing to look for, including for heirs of early users, a problem we covered in our crypto inheritance guide.
What This Means for You: A Last-Minute Checklist
If you think you may hold Sprout coins, work through these steps in order. This draws on the Zcash Community Forum recovery thread and the zcashd migration documentation.
- Copy before you do anything else. Make a second copy of every
wallet.datand old data folder you find, and never experiment on your only copy. Our encrypted USB drive guide explains how to store a file like this safely. - Identify what you have. Look for
zc...addresses, exported Sprout keys beginning withSK, or az_exportwalletbackup. - Choose a route. The forum thread names two for Sprout: the third-party Argos rescue wallet, estimated at hours at best and possibly days, and a constrained zcashd setup running behind a newer node, estimated at days to weeks. We have not tested these tools, so verify any download against the project’s official channels. Zallet, the new official wallet, does not support migrating Sprout keys or funds.
- Plan the destination. The community’s suggested path is Sprout to Sapling, then Sapling to Ironwood. Standard zcashd commands such as
z_sendmanyblock direct Sprout-to-Sapling sends, and zcashd’s documentation recommends its built-in migration tool over manual workarounds. - Get a confirmed transaction before activation. Only what is mined before block 3,543,405 counts. Once NU7 is live, software that builds v4 transactions will simply fail.
Be realistic about the clock. zcashd’s migration tool creates at most five transactions each time the chain reaches a 500-block interval, using randomized amounts. By our arithmetic, a 500-block interval takes about 10.4 hours at 75 seconds per block, and fewer than 800 blocks remained on Thursday morning, so that tool has time for only one or two rounds. A larger balance may not finish. Faster options exist if your wallet file already holds spendable note data, which Coindoo reports can be swept in seconds, but a scan from a bare key was estimated at about 26 GB of transfer and can take hours.
There is also a privacy trade-off. Value leaving Sprout passes through the transparent pool, which reveals the amount. Withdrawals slowed to about 40 ZEC on Wednesday, down from about 9,094 ZEC on Sunday, and Coindoo notes that thin late activity makes exits easier to link.
Watch Out for Recovery Scams
A hard deadline, a large sum and confused holders make ideal conditions for fraud. The forum’s guidance is blunt: never paste private keys, wallet files or seed phrases into a website, forum post or chat. Be suspicious of anyone who contacts you offering to “unlock” frozen Sprout coins after activation, because no recovery mechanism currently exists. When you are done, our Seed Phrase Backup Checklist can help you tidy up, and the Exchange vs Hot Wallet vs Cold Wallet checker can help you decide where the coins should live next.
What Changes for Everyone Else
Regular holders: no action is needed unless you hold Sprout coins. Update your wallet app as normal. Some exchanges may pause ZEC deposits and withdrawals around the upgrade, so avoid time-critical transfers tonight and check your exchange’s notices.
Payments: the first confirmation should arrive about three times sooner on average. However, ZIP 218 does not recommend cutting the number of confirmations that services require, so do not assume every deposit will be credited three times faster.
Node operators: Zebra 7.0.0 is required before activation. According to crypto.news, upgraded nodes will disconnect older peers, and the upgrade moves stored state from v28 to v29, so back up state/v28 first because going back to Zebra 6.x requires a full resync. Older nodes stay online but follow the pre-NU7 chain, so their balances and confirmations cannot be trusted.
Supply: ZIP 235 estimates only about 221.8 ZEC per year would be removed based on a sample of past blocks, so this is not a meaningful short-term supply shock.
What to Watch Next
- A clean activation. Watch whether block 3,543,405 passes without chain splits and whether block times settle near 25 seconds.
- The final Sprout balance. The number left at activation will show how many coins were stranded.
- Any recovery proposal. A future fix would need a new consensus change and community support. None is on the table today.
- Node updates. Zebra 7.0.0 has an eight-week support window rather than the usual 12, so another update should follow soon.
Frequently Asked Questions
Is my ZEC on an exchange at risk from the Sprout freeze?
Almost certainly not. The freeze only affects coins still held in the Sprout pool, which are overwhelmingly in old self-custody wallets. You may see a temporary deposit or withdrawal pause around the upgrade.
Can I get frozen Sprout ZEC back after NU7?
Not today. ZIP 2003 leaves open the theoretical possibility of restoring access in a later upgrade but warns it may never happen. Keep your wallet files safe in case a mechanism is ever added.
Does a Zcash seed phrase recover Sprout funds?
No. Sprout keys were not derived from a seed phrase, so you need the original wallet file or an exported Sprout key. A seed can only restore Sapling and later shielded funds.
Are the frozen coins being burned?
No. They remain part of issued supply but cannot be spent.
Do I need to buy a new hardware wallet because of NU7?
Not because of the freeze. A forum respondent told a Trezor holder the same thing. Transparent funds are not frozen, and Bowe has said wallets should not be significantly affected.
Gear That Helps With Old Wallet Files
You do not need to buy anything to get through NU7, but this episode shows how much depends on old files and backups:
- Apricorn Aegis Secure Key 3NX – a keypad-protected encrypted USB drive for a second copy of an old wallet file, which this story shows can matter more than a seed phrase. Check current price on Amazon
- Samsung T7 Portable SSD – fast external storage if you need room to run a node or scan the chain for old keys without filling your main drive. Check current price on Amazon
- Stainless steel seed phrase backup plate – a fire-resistant home for the seed behind your newer Sapling or Ironwood wallet once your coins have moved. Check current price on Amazon
- SentrySafe fireproof document safe – somewhere to keep old drives and backups together, so your heirs can find them when a future deadline like this arrives. Check current price on Amazon
This article is for informational purposes only and does not constitute financial advice.
