Bitcoin BIP-110 Enters Mandatory Signaling Phase With Miner Support Below 3%

Bitcoin Improvement Proposal 110 (BIP-110) entered its mandatory-signaling phase at block 961,632 on Saturday, with miners signaling support in just 51 of the preceding 2,016 blocks—equivalent to 2.53%, according to the BIP-110 monitor. That figure falls far short of the 55% threshold required for early activation.

Bitcoin Improvement Proposals are formal design documents that suggest changes to the Bitcoin protocol. While most soft forks activate after substantial miner signaling to ensure coordination, BIP-110 uses a mandatory-signaling mechanism that allows enforcing nodes to proceed even without majority miner support—a more forceful approach than typical deployment methods.

From block 961,632 onward, nodes enforcing BIP-110 began rejecting blocks that did not set version bit 4. Standard Bitcoin nodes, however, continued accepting both signaling and non-signaling blocks. A minority BIP-110 chain branch emerged shortly after but quickly fell behind the dominant chain.

Given the low signaling rate, a sustained rival chain appears unlikely without significantly greater miner participation. A BIP-110 branch with limited mining support could advance very slowly or cease producing blocks entirely.

The milestone marks a test of whether proponents can push forward a contentious consensus change without broad miner backing—a scenario that could separate enforcing nodes from the dominant chain and intensify an ongoing debate over how Bitcoin's block space should be utilized. The dispute echoes earlier divisions within the Bitcoin community over network utility, though BIP-110's mandatory-signaling approach differs from prior fork debates.

BIP-110 Proposes Temporary Restrictions on Bitcoin Data

Authored by pseudonymous developer Dathon Ohm, BIP-110 introduces additional consensus restrictions that would remain in effect for approximately one year.

Under the proposal, most new output scripts would be limited to 34 bytes, OP_RETURN outputs capped at 83 bytes, and certain data pushes and witness elements restricted to 256 bytes. Several Taproot features would also be temporarily limited. Unspent transaction outputs created prior to activation would be exempt from the new rules.

Supporters argue the restrictions would discourage inscriptions and other forms of non-monetary data that increase storage and bandwidth costs for node operators. Inscriptions, introduced through the Ordinals protocol in early 2023, enable users to embed data such as images and text directly onto satoshis on the Bitcoin blockchain. The practice has grown significantly and at times accounted for a substantial share of Bitcoin transaction activity, contributing to elevated fee environments that BIP-110 supporters view as harmful to Bitcoin's role as a peer-to-peer payments network.

Critics of the proposal, including Strategy Executive Chairman Michael Saylor and Blockstream CEO Adam Back, have warned that BIP-110 could fracture the Bitcoin network and lead enforcing nodes to reject transactions that remain valid under the network's existing rules.

Deployment Schedule and Contingency Plans

The proposal uses version bit 4 for miner signaling. Its deployment schedule designates blocks 961,632 through 963,647 as the mandatory-signaling window, during which BIP-110-enforcing nodes reject any blocks lacking the signal. The specification defines block 963,648 as the start of its locked-in state and block 965,664 as the point at which its transaction restrictions take full effect.

BIP-110 proponents have also discussed a more aggressive fallback option. On August 1, Bitcoin developer Chris Guida rebased preliminary code for a proof-of-work change originally authored by Bitcoin Knots maintainer Luke Dashjr. Guida described the code as a contingency in the event that miners actively oppose BIP-110, but noted that no activation date had been set. A proof-of-work change would alter Bitcoin's core mining algorithm, potentially invalidating existing specialized mining hardware and representing one of the most disruptive measures available in Bitcoin governance disputes.