Zecnero

Testnet network upgrade at block 16,529

By Zecnero ·

At block 16,529, expected around October 8, 2026 at 22:00 UTC, the Zecnero testnet switches on shielded payments, the Mainnet coinbase rule and a faster difficulty adjustment. The chain and balances stay.

The Zecnero testnet upgrades at block 16,529. At the current pace that block arrives around Thursday, October 8, 2026 at 22:00 UTC. The chain keeps running, balances stay, and so do the heights on the Genesis Miners wall.

At that block three rules switch on together, along with a fix for Orchard proofs built by wallets. They are the rules planned for Mainnet, where they apply from the first block. Every node, the pool, every miner and every wallet has to upgrade before block 16,529.

What changes

Payments are shielded

From block 16,529 only coinbase transactions may have transparent outputs. Transparent nm… addresses receive mining rewards: the miner’s reward and the founder output. Every other transaction pays Sapling or Orchard outputs, and that includes change. A payment to an nm… address is refused by the network.

Mined coins are shielded before they are spent

This is the Mainnet coinbase rule. Once mined coins have 100 confirmations, the wallet shields them into your Sapling address. From there you can spend them.

Difficulty reacts faster

Zecnero sets difficulty with ASERT. Its half-life says how fast the target follows the hashrate. It is 2 hours today and becomes 1 hour at block 16,529. The formula is re-anchored at the upgrade block, so difficulty carries on from where it is, with no jump.

The testnet showed why. On September 25 a miner with about two thirds of the hashrate left, and blocks came about every two minutes for hours while difficulty caught up. With a 1-hour half-life that recovery takes about half as long.

Orchard

The fix for wallet Orchard proofs switches on with the upgrade. It makes proofs built by wallets match the corrected circuit the node verifies. Full Orchard support in the wallet comes later, and stays off until it passes its tests.

Upgrade before block 16,529

The release is testnet-v0.2.0, out now on the file host, signed as usual.

  • With the one-command install: run zecnero-miner update. It works for pool and solo mining.
  • On the pool: log in with a Sapling address before block 16,529. The pool refuses nm… logins from then on, because it can only pay shielded. zecnero-miner update asks for a Sapling address. If you have none, zecnero-miner pool-login new makes a wallet and shows its seed words to write down. Your worker name stays.
  • Pool balances on an nm… login: from block 16,469, about 75 minutes before the upgrade, the pool pays out every nm… balance, whatever its size. Anything credited to an nm… login after that goes to the Sapling address you register, signed with your mining key: zecnero-miner register-payout ntestsapling1…, or the form at pool.zecnero.org/register.
  • Solo with your own node: the same update installs the new node. Rewards still go to your nm… address. Shield them with the wallet before you spend them.
  • With your own xmrig-zecnero: the algorithm does not change. For the pool, set -u to your Sapling address.
  • Wallets: update to 0.2.2, from the release folder or the wallets page. Wallet 0.2.1 stops syncing at block 16,529. It refuses payments to nm… addresses and sends change to your Sapling address. To receive coins, give out your Sapling address (ntestsapling1…). The faucet pays Sapling addresses.

Nodes that do not upgrade

A node that has not upgraded stops at block 16,528 and loses its peers. Its status can still look healthy, and a solo miner on it may keep mining a chain nobody else follows. Blocks mined that way never count. Check your height against the explorer. Upgrade the node and start it again, and it carries on with the chain. If your node mined blocks of its own after block 16,528 and does not move on after the update, the recovery steps will be on the blog; until then, ask in Discord.

Timeline

  • October 4: testnet-v0.2.0 on the file host, and this announcement with the height, about four days ahead.
  • October 7, 22:00 UTC: a reminder, with about a day to go.
  • Around October 8, 20:45 UTC: block 16,469. The pool pays out every nm… balance.
  • Around October 8, 22:00 UTC: block 16,529. The new rules apply from that block on.

Questions go to Discord, and bugs to GitLab. Testnet coins have no value. Mainnet is planned for Q4 2026.

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