TL;DR

• Jenner is scheduled for BSC testnet on October 28, 2026.
• Node operators must upgrade before activation.
• Changes include Payment Lane and millisecond timestamps.
• Jenner enables functionality for a new Compliant Asset Standard (CAS20)

The Jenner hard fork introduces changes to payment capacity, native asset controls, and the timestamp information available to smart contracts on BNB Smart Chain (BSC).

Validators, node operators, block builders, and application developers should review the changes and prepare for testnet activation. This notice covers the upgrade requirements, included proposals, and compatibility checks.

Upgrade Scheduled & Required Action

Jenner is scheduled for testnet on October 28, 2026. Confirmed mainnet timing will be announced separately.

All BSC nodes must run a compatible client release before their network’s activation. Check the release instructions for your client and network, including the exact activation time, before scheduling the upgrade.

For Chapel testnet operators using Reth, reth-bsc v0.1.3 is available for Jenner. Review its RPC compatibility changes before replacing the binary and restarting. Operators using the BSC Geth client should follow the release instructions for that client.

The official Jenner upgrade notice provides the reference for rollout updates and upgrade information.

What Changes in Jenner

Payment Lane: Reserved capacity for eligible payments

BEP-703 introduces Payment Lane, which reserves 5% of each block’s gas capacity for qualifying payment transactions by default. Governance can adjust that share up to a protocol maximum of 10%.

Eligible payments include nonzero BNB transfers to accounts without code and eligible transactions sent to governance-listed payment contracts. The contract list starts empty, so stablecoins and CAS20 tokens require separate governance approval to qualify.

Payments can compete for capacity beyond the reserved share. General transactions cannot use unused payment capacity. Existing fee and transaction-ordering rules remain in place, and the reservation does not guarantee inclusion for an individual payment.

Payment providers should review the transaction eligibility rules. Block builders must account for the reservation when constructing blocks.

CAS20: Native asset controls, coming soon

BEP-702 introduces the Compliant Asset Standard, CAS20, for assets such as stablecoins and tokenized real-world assets. It provides protocol-native token functionality with transfer policies, allowlists and blocklists, pausing, and separate mint, burn, and seizure roles.

Jenner includes the underlying capability. Token creation and policy-registry updates require separate activation by a governance-appointed administrator. CAS20 retains BEP-20 selector and event compatibility; its technical controls do not themselves establish legal compliance.

CAS20 is coming soon. A separate announcement will cover its availability, functionality, and integration details.

Millisecond timestamps for smart contracts

BEP-706 adds a precompile at address 0x70 that returns the executing block’s timestamp in milliseconds. Applications can use it for timing-sensitive logic such as quote expiry, auction cutoffs, and price-feed freshness checks.

Contracts must explicitly call the precompile to use it. Existing block.timestamp behavior remains in seconds.

The change exposes finer timing precision already present in block headers. It does not change block speed or provide stronger timing guarantees than the existing validator-supplied block timestamp.

RPC compatibility & block builder updates

Reth operators and teams using its RPC endpoints should review a compatibility change in reth-bsc v0.1.3. It applies immediately after upgrading, including before Jenner activates.

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. Overriding only time resets the millisecond remainder to zero.

The release also includes BEP-675 improvements to builder-proposed blocks: binary BidBlock submission over gRPC, stronger validation, and builder revocations that persist across restarts. These accompanying client improvements do not require a hard fork.

Review the Reth release notes for the full compatibility details.

Prepare for Testnet Activation

• Validators and node operators: Check the applicable client release and activation time, review compatibility changes, and complete the upgrade before activation.
• MEV block builders: Verify Payment Lane gas accounting and review the updated BidBlock submission interfaces.
• Application developers and integrators: Check affected RPC overrides and test millisecond timestamp integration where relevant. Payment teams should verify eligibility rules, while CAS20 integrations should account for separate feature activation.

Use the Jenner upgrade notice and your client’s release notes to track confirmed rollout details.