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Fork Freezes After Two
Bitcoin’s BIP-110 fork began at block 961,632 when nodes enforcing the proposal started rejecting blocks that did not signal support through version bit 4, but the enforcing branch produced only blocks 961,632 and 961,633 before stalling.
“only 51 of the previous 2,016 blocks signaled support, equivalent to 2.53%”
In the same split, AntPool mined a non-signaling block at height 961,632 that was accepted by the wider Bitcoin network, while BIP-110 nodes rejected it and followed an alternative signaling block produced using OCEAN’s infrastructure.
The minority chain’s stall was tied to mining economics: it inherited Bitcoin’s existing mining difficulty while receiving only a small fraction of hash rate, with only 51 of the previous 2,016 blocks signaling support, equivalent to 2.53%.
Because Bitcoin recalculates difficulty every 2,016 blocks, the BIP-110 branch still had to work through the remainder of that period before a conventional retarget could make mining easier, leaving it unable to maintain Bitcoin’s approximate 10-minute block interval.
LCX Exchange described the outcome as a fork that “sputtered to a halt after mining just two blocks,” with the branch falling dozens of blocks behind the main network.
Critics, Supporters, and Quotes
The split immediately became a dispute over whether enforcing a consensus rule without broad miner buy-in could work, with the mandatory signaling window running from blocks 961,632 through 963,647 even as the enforcing branch remained stuck at block 961,633.
Michael Saylor, executive chairman of Strategy, framed the result as proof that the fork mechanism could not command the network, posting on X: “Bitcoin worked exactly as designed. BIP-110 was free to fork, and the network was free not to follow.”
Saylor added a specific hashpower claim in the same post, saying “about 99.85% of Bitcoin's hash power stayed with Bitcoin,” while the BIP-110 branch “mined only two blocks and is already more than 80 blocks behind.”
Jameson Lopp, co-founder of Bitcoin security company Casa, echoed the rejection of the minority chain’s supporters, writing: “I won't be ‘welcoming back’ or unblocking any BIP-110 supporters,” after the fork stalled.
Meanwhile, the BIP-110 monitor data described the enforcing branch as frozen after two blocks while the non-enforcing Bitcoin chain advanced, with the gap widening as mandatory signaling continued despite miner rejection.
What’s at Risk Next
With the enforcing nodes rejecting blocks that did not signal version bit 4, the BIP-110 branch remained operationally constrained by the difficulty adjustment schedule, and the sources described the fork as effectively unable to catch up without additional hash power.
“transactions may be valid on both chains without reliable replay protection”
The BIP-110 state machine in the sources placed the next milestones beyond the stalled two-block start, with the mandatory signaling window closing at block 963,647 and the proposal’s restrictions not becoming ACTIVE until block 965,664.
One practical risk highlighted in the coverage was replay risk, because the sources warned that “transactions may be valid on both chains without reliable replay protection,” even while the enforcing branch lagged.
The same replay concern was paired with a broader technical critique from Blockstream CEO Adam Back, who warned that BIP-110’s consensus changes could “potentially make certain unspent transaction outputs unspendable,” raising stakes for how UTXOs might be treated.
As the minority chain stayed behind—while the dominant chain continued advancing—the sources framed the immediate consequence as a fork that could persist as a minority history without sufficient mining support to make confirmations practical.
