Bitcoin BIP-110 enters mandatory phase at 2.53% support

Bitcoin’s contentious BIP-110 test has moved from signaling into an actual chain split, and the first hours show miners overwhelmingly continuing to build on the existing Bitcoin chain.

The proposal entered mandatory signaling at block 961,632 on Aug. 8 after only 51 of the previous 2,016 blocks, or 2.53%, signaled support. Nodes enforcing BIP-110 then began rejecting blocks without version bit 4.

The latest available BIP-110 monitoring data on Aug. 9 showed the enforcing branch stalled at block 961,633 after producing only two blocks. Bitcoin’s non-enforcing chain had already reached 961,731, putting it 98 blocks ahead. The tracker also showed no BIP-110 signaling among the first 100 blocks of the new difficulty period on the dominant chain.

Bitcoin BIP-110 split widens after miner support stays low

The split began because BIP-110 applies different validity rules during its mandatory signaling window. According to the official BIP-110 specification, enforcing nodes must reject any block between heights 961,632 and 963,647 that fails to signal bit 4. Ordinary Bitcoin nodes do not impose that requirement, allowing them to continue following non-signaling blocks.

Roughnecks, a pseudonymous mining operation using OCEAN’s DATUM system, produced BIP-110 blocks 961,632 and 961,633. The branch then stopped advancing for about 15 hours in the latest monitor snapshot. Earlier Sunday, when the main chain stood at 961,721, the gap had already widened to 88 blocks.

The widening gap reflects the difference in computing power assigned to each chain. BIP-110 entered the current period with the same mining difficulty environment, but its enforcing branch has only a small fraction of Bitcoin’s hash power. Without more miners joining, it must continue finding difficult blocks slowly before reaching another difficulty adjustment.

That does not technically erase the minority branch. More hash power could still be directed toward it. However, the observed block production provides no evidence so far that enough miners are switching to close the accumulated work gap.

The 55% voluntary threshold was missed by a wide margin

BIP-110 allows an earlier lock-in if 1,109 of the 2,016 blocks in a difficulty period signal support, equal to 55%. The period ending at block 961,631 recorded just 51 signals, according to the monitoring data, leaving support at 2.53%.

Strategy Executive Chairman Michael Saylor had already argued before the deadline that the low signaling rate showed the proposal lacked broad mining support. His characterization that the data represented “not miner consensus” was his assessment of the signaling figures rather than a formal network governance determination.

Saylor and Blockstream CEO Adam Back opposed the proposal on broader grounds. Back warned that enforcing new consensus restrictions without wider agreement could divide participants, while supporters argue the restrictions are needed to discourage non-monetary data use. Those remain competing views about how Bitcoin block space should be governed.

BIP-110 would temporarily restrict several transaction structures once fully active. Most new output scripts would be limited to 34 bytes, OP_RETURN outputs to 83 bytes, and some data pushes and witness elements to 256 bytes. It would also restrict parts of Taproot for the proposal’s roughly one-year active period.

The chain split also creates a practical issue for holders. As crypto.news reported before mandatory signaling began, Bitcoin developer Kevin Loaec warned that signed transactions could potentially be recognized on both chains because BIP-110 does not automatically separate users’ pre-fork balances.

A holder attempting to transfer coins on the minority branch could therefore risk moving the corresponding BTC on the dominant chain if the same transaction is valid there and gets rebroadcast. The risk applies to the transaction inputs involved rather than giving another party control over an entire wallet. Leaving pre-split coins unmoved avoids creating a transaction that could be replayed.

The practical risk depends partly on whether markets, wallets or exchanges begin treating the minority branch as an asset worth transacting. With only two blocks mined so far, there is little evidence that such an ecosystem has developed.

Proof-of-work change remains a fallback, not a scheduled fork

Some BIP-110 supporters have prepared for the possibility that existing Bitcoin miners continue rejecting the proposal in practice. On Aug. 1, developer Chris Guida rebased experimental proof-of-work change code originally authored in part by Bitcoin Knots maintainer Luke Dashjr. The GitHub comparison contains 12 commits affecting 19 files, including code for selecting a different proof-of-work algorithm.

However, the code does not establish a scheduled network change. Guida described it as “just some code to have in our back pocket” and said no activation deadline had been set. His comments make the proof-of-work proposal a contingency rather than an announced hard fork with a fixed date.

Dashjr has continued supporting BIP-110 despite criticism and earlier rejected calls to withdraw it. Supporters maintain that temporary restrictions would reduce arbitrary data storage, while critics favor leaving block-space allocation to fees and individual node policies.

What happens next for BIP-110

The next protocol checkpoints are defined by block height rather than fixed dates. Mandatory signaling continues through block 963,647. Under the BIP specification, the deployment reaches LOCKED_IN no later than block 963,648, followed by ACTIVE at 965,664. Only then would the proposal’s reduced-data transaction rules begin.

Those heights could arrive on very different timelines across the two branches. Bitcoin’s dominant chain continues producing blocks at its normal pace, while the BIP-110 enforcing branch would need substantially more hash power to approach the same rate. At the latest retrieved snapshot, it remained 98 blocks behind after advancing only once beyond its alternative block 961,632.

The immediate metric to watch is therefore not another scheduled vote but mining activity. If miners begin extending the BIP-110 branch, its block production could resume. If hash power remains concentrated on Bitcoin’s existing chain, the gap will continue widening and the enforcing branch will face an increasingly difficult path to becoming the chain with the most accumulated proof of work.