BNB Chain details Jenner hard fork changes for BSC testnet
BNB Chain has published a Jenner hard fork upgrade guide for BNB Smart Chain, setting out protocol changes that affect payments, smart-contract timing and native asset controls ahead of testnet activation. The notice, published Oct. 22, says node operators must upgrade before activation, while confirming that mainnet timing will be announced separately.
Evidence and context
According to the BNB Chain blog post published Oct. 22, Jenner is scheduled for BSC testnet on Oct. 28, 2026. However, the provided enrichment notes a timing discrepancy: the official v1.8.1 release specifies Oct. 29, 2026 at 02:30:00 UTC. Because those sources conflict, the testnet date cannot be treated as unambiguously confirmed. Operators are therefore being told to verify the applicable client release and activation time before upgrading.
The guide says the upgrade introduces three main protocol changes. BEP-703 adds Payment Lane, which reserves 5% of each block’s gas capacity by default for qualifying payment transactions, with governance able to raise that share to a protocol maximum of 10%. The blog says eligible payments include nonzero BNB transfers to accounts without code and eligible transactions sent to governance-listed payment contracts. It also says the contract list starts empty, so stablecoins and CAS20 tokens would require separate governance approval before qualifying. Unused reserved capacity cannot be taken by general transactions, and the reservation does not guarantee inclusion for any individual payment.
BNB Chain also says BEP-702 introduces CAS20, a protocol-native standard for assets such as stablecoins and tokenized real-world assets. The guide says Jenner includes the underlying capability, but token creation and policy-registry updates require separate activation by a governance-appointed administrator. It adds that CAS20 retains BEP-20 selector and event compatibility, while its technical controls do not themselves establish legal compliance. The company says a separate announcement will cover CAS20 availability, functionality and integration details.
Another change comes from BEP-706, which adds a precompile at address 0x70 that returns the executing block’s timestamp in milliseconds. BNB Chain says applications can use the precompile for timing-sensitive logic such as quote expiry, auction cutoffs and price-feed freshness checks, while existing block.timestamp behavior remains in seconds. The blog says the change exposes finer timing precision already present in block headers and does not alter block speed or improve the timing guarantees of the validator-supplied timestamp.
The notice also highlights RPC compatibility changes in reth-bsc v0.1.3 for Chapel testnet operators and anyone using Reth RPC endpoints. For eth_call, eth_estimateGas, debug_traceCall and eth_simulateV1, a supplied blockOverrides.prevRandao must encode the millisecond remainder, from 0 to 999, as a 32-byte hex value. The time field remains in seconds, and overriding only time resets the millisecond remainder to zero. BNB Chain says the release also includes BEP-675 builder improvements, including binary BidBlock submission over gRPC, stronger validation and builder revocations that persist across restarts; those improvements do not require a hard fork.
The blog directs validators, node operators, block builders and application developers to review the applicable client release, check compatibility changes and complete upgrades before activation. It also advises MEV block builders to verify Payment Lane gas accounting, and payment teams to review eligibility rules. The market data supplied alongside the notice shows BNB at $732.36 as of Oct. 22, down 1.75% on the day, with a market capitalization of $96.31 billion.