BNB Chain Jenner Hard Fork: Testnet Fork on October 29, 2026, Mainnet Date Not Yet Set

1. What is the Jenner hard fork?

Jenner is the BSC hard fork that follows Pasteur, the security fork before it, and comes a few months after the Fermi fork of January 2026 that brought blocks down to 0.45 seconds. The scope is listed in BEP-718, the meta proposal, and in BNB Chain's announcement of October 22, 2026: three consensus changes plus client-side improvements that need no fork.

BEP-703, Payment Lane, reserves a share of every block's gas for payment transactions. BEP-702, the Compliant Asset Standard or CAS20, puts a fungible token standard for stablecoins and tokenised assets into the protocol itself as stateful precompiles, with roles for minting, burning, pausing and seizure and shared allowlists and blocklists; it keeps the BEP-20 function selectors and events, so wallets need no change. BEP-706 adds a precompile at address 0x70 that returns the block's timestamp in milliseconds. The BEP-675 improvements to the builder interface (binary BidBlock submission over gRPC, builder revocations that survive restarts) ship in the same client release but are not consensus changes.

BNB Chain's upgrade page also lists BEP-714, which cuts the wait before a backup validator steps in from 2 seconds to 1 second. That proposal does not appear in BEP-718 or in the v1.8.1 release notes, so we treat its inclusion as open until a client release confirms it.

2. When is the Jenner hard fork? Key dates

The dates below come from the client releases and from BNB Chain's own announcements. The status column is what we can confirm as of October 25, 2026.

3. What is Payment Lane and will it change BNB gas fees?

Payment Lane is an accounting rule for block space, not a fee change. BSC has no base fee: the field is zero in every block, so getting in depends on the priority fee you bid and on the floor price validators publish, 0.05 gwei at the time of writing. When blocks fill, a stablecoin transfer or an exchange withdrawal bids against arbitrage bots and loses, even though it needs very little gas. BEP-703 answers that by reserving a share of each block for payments: general transactions may use at most the gas limit minus that share, while payment transactions may use the whole block. If no payments show up, the reserved gas stays empty rather than going to general traffic.

The default share is 5% (the parameter PAYMENT_LANE_RATIO is 500 out of 10,000), and governance can move it anywhere above zero up to a hard cap of 10%. Mainnet blocks carried a gas limit of 70,000,000 on October 25, 2026 (block 129,612,382 on the public RPC), so the lane would be 3,500,000 gas, room for about 166 plain BNB transfers of 21,000 gas each in every 0.45-second block. On October 25, 2026 the Normal gas price on our tracker is 0.05 gwei, a BNB transfer costs <$0.001 and a swap ~$0.007, with blocks far from full, so the lane would sit idle most of the time. It only binds during congestion, and that is the point.

BNB Chain and Ethereum right now

Two things the lane does not do. It does not lower or raise anyone's gas price: BEP-703 states that no new ordering, priority or fee rule is introduced, payments bid under the same rules and pay full fees, and the announcement adds that the reservation does not guarantee inclusion for any individual payment. And it does not cover stablecoins yet. A transaction counts as a payment only if it is a non-zero BNB transfer to an account without code, or a call to a contract on the governance-managed payment list, which starts empty. A USDT transfer on BSC is a contract call, so it qualifies only after a governance vote adds that contract. BNB Chain says stablecoins and CAS20 tokens need that separate approval.

For the fee you pay today, see the BNB Chain gas tracker, which explains the 0.05 gwei floor and the zero base fee. For how gas prices work in general, the gas fees guide covers base fee, priority fee and gas limit.

4. What changes for developers?

Millisecond timestamps. BSC headers have carried a millisecond value since BEP-520, stored in the last two bytes of the mix digest, but the EVM only exposed whole seconds. BEP-706 adds a precompile at 0x70 that returns the executing block's time in milliseconds since the Unix epoch as a 32-byte integer, for 20 gas, ignoring calldata. block.timestamp keeps returning seconds, so deployed contracts behave as before. The value is validator-supplied and offers no stronger guarantee than block.timestamp; it just has finer resolution.

An RPC change that bites before the fork. From bsc v1.8.1 and reth-bsc v0.1.3 onward, if you pass blockOverrides.prevRandao to eth_call, eth_estimateGas, debug_traceCall or eth_simulateV1, the value must encode the millisecond remainder (0 to 999) as a 32-byte hex number. This applies as soon as the node you talk to upgrades, before Jenner activates. The time override stays in seconds, and overriding only time resets the millisecond remainder to zero. If your tooling simulates against BSC nodes with block overrides, test it this week.

CAS20. The hard fork installs the standard's code on every node, but token creation and policy-registry writes stay off until a governance-appointed administrator activates each feature in the ActivationRegistry at 0x7020000000000000000000000000000000000001. Reads are never gated. CAS20 tokens keep the BEP-20 selector and event surface, so existing integrations will read balances and transfers without changes once tokens exist. BNB Chain says availability will get its own announcement.

Nothing else moves. Transaction types, the JSON-RPC methods you use to send transactions and the fee fields are unchanged, so SDKs such as ChainGate keep working. If you run a payment product, check whether your flows are bare BNB transfers (eligible from day one) or contract calls (eligible only once listed), and watch the governance proposals that add contracts to the list.

5. What do node operators, validators and builders have to do?

Chapel testnet: upgrade before 02:30 UTC on October 29, 2026. bsc v1.8.1 and reth-bsc v0.1.3 are marked mandatory for Chapel node operators, MEV builders and sentry operators, and both are binary replacements: read the RPC changes, swap the binary, restart. A node left on an older version will reject Jenner blocks and fall off the testnet at the fork.

Two things to check in the Geth client. The MEV gRPC service is on by default when MEV and BidBlock submission are enabled and listens on the HTTP bind address on port 8552; make sure the port is free, change it with [Eth.Miner.Mev] GRPCPort in config.toml, or turn it off with --mev.grpc.disable. Builders should also verify their Payment Lane gas accounting, because a block whose general gas plus the larger of payment gas and the lane quota exceeds the gas limit is invalid, and under the BEP-675 bid path an invalid block triggers builder revocation.

Mainnet: nothing yet. Neither release schedules mainnet, and running v1.8.1 on a mainnet node changes nothing there until a mainnet release with its own timestamp appears. When it does, the same rule applies: every mainnet node, builder and sentry must upgrade before the fork time.

6. Do BNB holders and BSC users need to do anything?

No. There is no new token, no migration and no wallet action for the testnet fork or for mainnet later. Your BNB, your BEP-20 tokens and your addresses do not change. Anyone asking you to "upgrade" or "migrate" your BNB for Jenner is running a scam.

What you may notice, once mainnet forks, is only visible under load: in a congested block, a plain BNB transfer has reserved room it did not have before, so it should confirm in the next block more often instead of waiting behind bot traffic. In quiet periods nothing changes, and the gas price stays at the validator floor. Exchanges sometimes pause BSC deposits and withdrawals for a short while around a mainnet fork; that is the only practical disruption to plan for, and only once a mainnet date exists.

7. What is confirmed and what is still open?

8. What comes after Jenner?

The next steps are the mainnet release with its timestamp, the first governance proposals that list payment contracts or activate CAS20, and the separate CAS20 availability announcement BNB Chain has promised. We will update this page at each of them, and the update log below records what changed and when.

In the meantime, the BNB Chain gas tracker shows the live gas price and what a transfer costs, the gas fees guide explains the mechanics Payment Lane leaves untouched, and the EVM chain ID list has the chain IDs of BSC mainnet (56) and the Chapel testnet (97) if you are adding them to a wallet to test.

Updates to this article

• October 25, 2026: first published. Testnet activation time taken from the bsc v1.8.1 and reth-bsc v0.1.3 release notes, scope and defaults from BEP-703, BEP-706, BEP-702 and BEP-718, and from BNB Chain's announcement and upgrade page of October 22; the mainnet gas limit was read from the public BSC RPC on October 25.

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