# Zcash activates 25-second blocks on public testnet ahead of a November 5 mainnet target

The NU7 upgrade cuts block time from 75 seconds, sends 60% of transaction fees to a reserve for future mining rewards, and disables the old Sprout shielded pool, Zcash's original privacy pool.

- Published: 2026-10-05T05:31:33.542Z
- Canonical: https://polylog.news/crypto/2026-10-05/zcash-activates-25-second-blocks-on-public-testnet-ahead-of
- Publisher: Polylog (Crypto desk)
- Section: crypto
- Sources: [CoinDesk](https://www.coindesk.com/tech/2026/10/05/zcash-s-25-second-blocks-go-live-on-public-testnet-ahead-of-schedule), [Crypto Briefing](https://cryptobriefing.com/zcash-nu7-upgrade-activates-testnet/), [Cointelegraph en Español](https://cointelegraph.es/news/zcash-nu7-testnet-activation-november-mainnet)

Developers of Zcash (ZEC) switched on the NU7 network upgrade on the public test network, reducing the target block time from 75 seconds to 25 seconds, [CoinDesk reported](https://www.coindesk.com/tech/2026/10/05/zcash-s-25-second-blocks-go-live-on-public-testnet-ahead-of-schedule). The upgrade activated at block 4,465,026, [Crypto Briefing reported](https://cryptobriefing.com/zcash-nu7-upgrade-activates-testnet/), ahead of the schedule developers had published. The test lets exchanges, wallets and node operators run their software against the new block timing before the mainnet launch.

Faster blocks change how quickly a payment is final in practice. A service that waits for three confirmations would wait about 75 seconds instead of 225 if it kept the same requirement. Three times as many blocks would also increase issuance unless the reward changes, so NU7 reduces the reward for each block to keep ZEC's issuance schedule intact. The upgrade also sends 60% of transaction fees to a reserve that will fund future mining rewards. That change gives the network a fee-funded security budget as the block subsidy declines.

NU7 also disables transactions that use Sprout, the original Zcash shielding system. Holders who still have funds in Sprout must move them before the upgrade if they want to keep access through the existing system. Developers plan to review the test results and decide on mainnet activation on October 20, with the mainnet date targeted for November 5, [Cointelegraph en Español reported](https://cointelegraph.es/news/zcash-nu7-testnet-activation-november-mainnet).

## What this means

The fee reserve is the more important change over the long run. Bitcoin and every other capped-supply proof-of-work chain face the same question: how to pay miners once block subsidies shrink. Zcash is testing a protocol-level answer that sets aside part of today's fees to fund future mining rewards. Shorter blocks benefit payment processors and exchanges because they can credit deposits sooner. They also add risk for miners and node operators, because faster blocks usually produce more orphaned blocks (valid blocks that lose out to a competing block) and require more bandwidth. Sprout holders who do not migrate are exposed directly. The market has already priced Zcash as a privacy asset. A working fee-to-security mechanism has not been priced in. If testnet stability holds through the October 20 review, the likelier outcome is mainnet activation on November 5 and a few weeks of exchanges adjusting their confirmation counts. A rise in orphaned blocks or chain reorganizations on testnet that forces the date to slip would prove this read wrong.

## What to watch

- The October 20 developer decision on mainnet activation. A delay would show that 25-second blocks caused stability problems on testnet.
- Whether major exchanges cut the number of Zcash confirmations they require. Lower requirements are what turn faster blocks into faster payments for users.
- The value of funds still held in Sprout as the deadline nears. A large remainder would show how much value sits in addresses that are lost or unattended.