Less than two weeks until BIP-110 mandatory signaling

Less than two weeks remain before Bitcoin nodes enforcing BIP-110 begin rejecting blocks that do not signal version bit 4. The mandatory signaling window is expected to open around Aug. 9, 2026 at block 961,632; as of July 27 the chain tip was near block 959,842, roughly 1,790 blocks away.

Miner signaling for BIP-110 has increased from under 1% a few weeks ago to about 2.64% today. Most of that support comes from the Ocean pool and a set of smaller, independent miners, including Roughnecks, SoV, Barefoot Mining, 234 Alberta, Peer to Peer Money and several others.

Large pools that control the lion’s share of global hashrate-Foundry, Antpool, ViaBTC and F2pool-have not committed to signaling. Foundry has opened a client vote that counts each customer’s average hashrate toward a weighted decision. The pool’s default is a No vote for non-responding clients, and it will switch to signaling only if more than 51% of participating weighted hashrate votes Yes.

Foundry’s share of the network is estimated between about 23% and 33% depending on the measurement period. A decision by Foundry to begin signaling would immediately change the signaling totals because of the pool’s size.

The only client enforcing BIP-110 is a Bitcoin Knots fork. Reachable nodes running that implementation are roughly 22% of the network. Bitcoin Core nodes, which make up most reachable nodes, are not enforcing the proposal.

BIP-110, authored under the name Dathon Ohm and earlier circulated as BIP-444, proposes temporary limits on certain data fields in transactions. The rules target Ordinals-style inscriptions, oversized OP_RETURN payloads and similar data-heavy uses while leaving ordinary payment transactions, standard Taproot spends and Lightning channel operations unchanged. If enacted, restrictions would begin at block 965,664 and expire automatically after 52,416 blocks, about one year.

The deployment uses a modified BIP-9 path. It required 1,109 of 2,016 blocks (55%) within a single difficulty period to lock in early. If that threshold is not reached, the proposal proceeds toward a forced lock-in at block 963,648 and then activates at block 965,664. Between those points is the mandatory signaling window from block 961,632 through 963,647, during which nodes enforcing BIP-110 reject any block that does not carry the designated version bit regardless of its proof-of-work.

If signaling shares remain low when block 961,632 arrives, two competing chains could emerge: one followed by nodes enforcing BIP-110 and another followed by legacy nodes and the majority of miners. Legacy nodes will continue following the chain with the most accumulated proof-of-work. A minority chain composed of signaling miners would likely advance more slowly until the next 2,016-block difficulty adjustment.

Debate over BIP-110 has included technical and economic arguments. Luke Dashjr, a Bitcoin Knots developer, wrote on X in July that “Removing rules is a hardfork” and characterized rejecting BIP-110 as a “contentious hardfork attempt.” Alex Thorn, head of research at Galaxy Digital, wrote on X that “OP_RETURN blockspace usage hasn’t increased much since Bitcoin Core v30 was released” and estimated oversized OP_RETURNs consume less than 0.1% of blockspace.

The coming days will show whether any of the largest pools change position, whether major exchanges clarify which chain they would recognize if competing chains appear, and how miners behave once the mandatory window opens. Current signaling remains concentrated in a small portion of the network as the deadline approaches.