BIP-54 approval runs into F2Pool opposition

Bitcoin developers completed BIP-54, a four-part consensus cleanup, in May 2026. The proposal aims to close several long-standing protocol edge cases, but formal activation on mainnet is uncertain after the founder of the major mining pool F2Pool said he will not pre-signal for the change.

BIP-54, titled “Consensus Cleanup,” was authored by Antoine Poinsot and Matt Corallo. Corallo first proposed related fixes in 2019; Poinsot expanded the work in late 2023 and early 2024. The draft received its BIP-54 designation in April 2025 and reached completion following testing and implementation in May 2026.

The proposal makes four specific rule changes. First, it would add timestamp limits at the start and end of each 2,016-block difficulty period to block time-manipulation attacks that can lower mining difficulty. Second, it would cap legacy signature operations in pre-SegWit transactions at 2,500 sigops to reduce the risk of blocks that are valid but costly to verify. Third, it would ban 64-byte transactions that can mimic internal Merkle-tree nodes and mislead some lightweight wallets. Fourth, it would require new coinbase transactions to include block-height-linked values to guarantee uniqueness and allow removal of older duplicate-transaction checks.

Some software and pools are already adopting parts of the proposal. Current Bitcoin Core builds include related policy protections, a Signet test environment called Bitcoin Inquisition is running BIP-54 tests, and pools including MARA and ViaBTC have begun producing compatible coinbase transactions voluntarily. Despite those preparations, BIP-54 requires a formal activation path on mainnet, typically the BIP-9 miner signaling mechanism, which needs broad miner support.

On Aug. 10, Wang Chun, co-founder of F2Pool, posted on X that the pool will not signal for BIP-54 before a formal majority is reached, although it would update mining nodes if the proposal later attained the required support. He criticized bundling four changes in one package and questioned whether some addressed risks justify the coordination and software updates a soft fork requires. Supporters of BIP-54 describe the proposal as defensive changes meant to reduce rare consensus risks rather than add new script features.

The dispute over activation follows the collapse of BIP-110. BIP-110, which sought to limit certain nonfinancial data in transactions, failed to attract significant miner support; a small chain enforcing it stalled after producing only a few blocks near block 961,635. That episode preceded the current debate over how and when to approve consensus changes.

Next procedural steps include whether developers file a formal BIP-9 signaling specification, further miner readiness announcements, and whether additional major pools change their positions. Observers will monitor miner signaling levels, any formal activation proposal, and continued testing on Signet and in client releases.