BNB Chain will activate the Pasteur hard fork on BNB Smart Chain at 02:30 UTC on Aug. 25, 2026.
Summary
- BNB Chain will activate the Pasteur hard fork at 02:30 UTC on mainnet August 25.
- Node operators must install version 1.7.7 and remove EnableBAL before the scheduled mainnet activation deadline.
- Three proposals strengthen bridge validation, validator governance and builder submitted block processing across BSC mainnet.
- QANet testing raised throughput from 1,237 to 2,324 TPS without changing block times or finality.
- The reported performance gains came from controlled testing and are not guaranteed after mainnet activation.
The mandatory upgrade introduces three proposals covering bridge verification, validator governance and block-processing capacity.
All BSC mainnet nodes must run client version 1.7.7 before activation, according to the official release. Regular users and most application developers do not need to migrate funds or change their software.
Pasteur strengthens BNB Chain bridge verification
BEP-682 changes how BSC validates blocks used for cross-chain transfers. The network checks validator signatures before accepting information from another chain, ensuring that the required voting threshold approved the block.
The previous process did not confirm that every validator appeared only once in a submitted validator set. A specially constructed set could theoretically repeat one validator and count its voting power more than once. BEP-682 rejects duplicate entries, making the threshold reflect a genuine validator supermajority.
As previously reported, Pasteur differs from recent upgrades that primarily reduced block times. Its security changes focus on cross-chain transfers and validator authority.
Validator controls close key-rotation gaps
BEP-695 addresses what happens when validators rotate their consensus keys. After Pasteur, an old consensus key will lose its administrative authority instead of retaining privileges following a rotation.
Pending slash evictions will also follow validators to their new keys. This prevents a validator from avoiding an outstanding eviction by changing keys. The proposal also blocks blacklisted addresses from using signature-based governance voting methods to bypass restrictions applied to direct votes.
These measures affect BSC staking and governance system contracts. BNB Chain says developers do not need to migrate existing applications because the changes occur at the protocol and system-contract levels.
BEP-675 moves work outside the critical path
BEP-675 allows builders to submit blocks they have already executed. Validators can check the proposed block against consensus rules, sign and broadcast it, then complete full verification outside the time-sensitive production path.
On QANet, an internal test environment designed to reflect BSC’s cross-region validator setup, processing within that critical path fell from 125 milliseconds to 15 milliseconds. Average block gas use increased from 46.35 million to 84.15 million against the existing 100 million limit.
Throughput rose from 1,237 to 2,324 transactions per second during the same tests. The block interval remained at 450 milliseconds, while finality lag did not change. BNB Chain cautioned that these figures came from controlled testing rather than live mainnet activity.
Builders adopting the new path must operate full nodes because they will produce fully executed blocks. Legacy block bids will remain available, although they provide builders with less time to fill blocks.
Node operators must install v1.7.7
Node operators must replace their existing binary with version 1.7.7 before activation. They must also remove [Eth] EnableBAL from config.toml; otherwise, the updated client will fail to start.
The release recommends removing [TxPool] OverflowPoolSlots, although the client will silently ignore that field. Several command-line flags are also obsolete or inactive, including –journalfile, –enablebal and –txpool.overflowpoolslots.
Pasteur has operated on BSC testnet since July 21. Following mainnet activation, operators and developers will monitor whether the capacity gains measured on QANet carry over to live traffic. No comparable mainnet performance increase is confirmed yet.
Earlier network changes reduced BNB Smart Chain block times. Pasteur instead aims to make greater use of existing block capacity while closing validator and bridge security gaps.
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