The Bitcoin BIP-110 mandatory signaling period began on August 7 at block 961,632, but miner support stood at only 2.53%. Supporting nodes immediately rejected non-signaling blocks, splitting off a minority chain, effectively rendering BIP-110 as a UASF a failure.
(Prior context: Has the Bitcoin "civil war" ended? BIP-110 hostile takeover attempt currently has less than 1% of supporting hash power)
(Background supplement: Michael Saylor Double Strikes BIP-110 Soft Fork: Bitcoin Needs Neutrality, Not “Monetary Purity”)
The Bitcoin network split into two branches at block 961,632 early this morning (the 9th), but this split was not a standoff between two opposing forces—it was a one-sided defection. BIP-110 supporters, immediately after the mandatory signaling period began, rejected mainchain blocks and moved onto a minority chain recognized only by themselves.
The forked block is block 961,632. AntPool, one of Bitcoin’s largest mining pools, mined the first block that did not signal BIP-110 version bit 4, which was accepted by the mainstream Bitcoin network, but nodes enforcing BIP-110 rules rejected it outright. As of 10:00 AM Taiwan time this morning, the main chain has reached block 961,659, while the BIP-110 chain is stuck at block 961,633, having only mined a second block—26 blocks behind.
What are "signaling" and the "mandatory signaling period"?
In Bitcoin soft fork upgrades (such as past Taproot or SegWit), a "Miner Signaling" mechanism is typically employed:
- Voluntary signaling period: After the upgrade proposal is released, miners who support the upgrade will include a specific marker (e.g., versionbit 4 used by BIP-110) in the block header of the blocks they mine, signaling to the entire network, "I support this change."
- Mandatory Signaling Phase: If, at the end of the voluntary signaling period, the support rate does not reach the predefined high threshold (e.g., 55% or 95%), but the proposal has set a "hard deadline," the network enters the mandatory signaling phase. During this period, nodes that enforce the proposal will require all newly mined blocks to include a support marker. Any block without the support marker will be directly rejected by these nodes as an "invalid block."
BIP-110 Rules and Timeline
BIP-110, written by the anonymous developer Dathon Ohm, is formally titled "Reduced Data Temporary Soft Fork." It proposes a series of consensus-layer restrictions lasting approximately one year, aimed at curbing the storage of non-financial data on the Bitcoin chain:
- Limit most new output scripts to 34 bytes
- OP_RETURN output limit: 83 bytes
- Limit part of the data push and witness elements to 256 bytes
- Temporarily restricting certain Taproot features
- Exemption for unspent transaction outputs (UTXOs) created prior to activation
These restrictions will take effect at block 965,664 and will be automatically lifted after 52,416 blocks (approximately one year).
55% threshold vs 2.53% current status
Bitcoin upgrades typically require broad consensus among miners. BIP-110 adopts a modified BIP9 deployment mechanism, requiring only 55% miner signaling (1,109 out of every 2,016 blocks over two weeks), a much lower threshold than the traditional 95%. However, if natural signaling is insufficient, a mandatory signaling window is triggered—which is what occurred this morning.
According to the BIP-110 Monitoring Page, in the final signaling period before the split, only 51 blocks transmitted support signals, accounting for 2.53%, far short of the 55% threshold. The support signals primarily came from Ocean Pool, which has been the most active supporter since the first BIP-110 block appeared in March 2026.
The adoption rate of nodes supporting BIP-110 software (primarily the Bitcoin Knots variant) is estimated to be between 2% and 8%, though these figures themselves are also contested.
Critics: This will harm Bitcoin
Critics of BIP-110 have long warned that this path would lead to a split. Adam Back, co-founder of Blockstream, stated plainly on X: “This simply won’t work—it breaks multiple mechanisms, lacks both technical consensus and ecosystem consensus, and has all four fatal flaws. Everyone hates bloat, but this isn’t the way; you’ll hurt yourselves.”
Bitcoin security expert Jameson Lopp released a detailed analysis calling BIP-110 "reckless and doomed to fail," citing risks of fragmentation, potential creation of unspendable UTXOs (Taproot edge cases), the inability to truly prevent data storage long-term (as data can be embedded in other ways), and the compatibility burden on wallets, Miniscript tools, and pre-signed transactions.
In July, MicroStrategy Executive Chairman Michael Saylor published an 110-point argument opposing BIP-110, with the core claim that consensus rules should address proven threats, not traders’ “perceived intentions.” He wrote: “Bitcoin does not need guardians of purity; it needs neutral guardians.”
The market did not react.
After the split message was announced, Bitcoin's price oscillated around $65,000 without significant volatility. This contrasts with the smooth transition during the Taproot soft fork activation in November 2021, which garnered broad miner support prior to lock-in and left no persistent minority chain.
What sets this split apart is that BIP-110 entered the mandatory phase with almost no miner support, resulting in a minority fork chain that started behind from the beginning. This chain does not create its own independent asset; its survival depends on whether miners continue to support it, and its economic significance depends on whether exchanges, wallets, and infrastructure adopt it. So far, none of these conditions appear promising.
Can BIP-110 make a comeback by sheer force?
This split reveals the core dilemma of BIP-110 supporters: they can force a split through node enforcement, but without miner hashpower, they cannot sustain a competitive chain. Several developments are currently worth watching:
- Short-lived chain survival: If Ocean and Roughnecks continue mining, this chain may persist for several weeks, but difficulty adjustments will extend block times to several hours, effectively turning it into a low-frequency chain.
- Exchange and Wallet Position: Any exchange that supports both chains simultaneously faces replay attack risks. Most institutions almost certainly choose the mainnet.
- Contingency plan: On August 1, BIP-110 supporters discussed a more aggressive contingency plan; Bitcoin developer Chris Guida has updated Luke Dashjr’s earlier proof-of-work modification code, but no activation date has been set yet.
From a technical perspective, BIP-110 as an attempt at user-activated soft forks has demonstrated that consensus changes without miner support cannot be enforced by force. Bitcoin’s “heaviest chain rule,” where the chain with the most PoW prevails, remains an unbreakable physical law.
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