The BIP-110 replay attack risk materialised faster than most anticipated: the minority chain mined just two blocks before stalling, according to the BIP-110 official site, which simultaneously published a guide for users wanting to switch back to the main Bitcoin chain using pre-RDTS (Reduced Data Temporary Softfork) software.
The split triggered at block 961,632 on 8 August after miner support fell well short of the activation threshold. Bitbase reported that only 51 of the preceding 2,016 blocks signalled support, equating to 2.53%, against the 55% required for early activation.
The BIP-110 Replay Attack Risk, Explained
Bitcoin developer Kevin Loaec warned holders against moving coins following the split, and the mechanics are straightforward. At the moment of separation, both chains share an identical transaction history. A holder with 10 BTC before the fork controls 10 coins on each resulting chain.
The problem: BIP-110 does not include built-in replay protection, and the proposal’s substantive data restrictions are not scheduled to activate until block 965,664. Until each chain accumulates outputs unique to its own history, a transaction that moves forked coins on the minority chain is structurally identical to a transaction on the main chain.
A buyer acquiring BIP-110 coins can copy the signed transaction and broadcast it on mainnet. If the network accepts it, the seller’s real BTC moves to the buyer’s address. Only the inputs in that specific transaction are exposed, not the entire wallet, but transaction fees would be charged on both chains. Loaec noted that large holders are higher-value targets: a replay involving a bigger input set produces a proportionally larger return for the attacker.
The BIP-110 replay attack risk drops to near zero for holders who simply leave their coins unmoved. No signed transaction, nothing to replay. The complication arises the moment someone tries to transact with or sell the forked balance before coin-splitting tools are available from wallets or exchanges.
How the Chain Split Actually Played Out
The mandatory signalling window marked the transition from the miner-activated soft fork (MASF) phase into the user-activated soft fork (UASF) phase, as the MiCA Crypto Alliance outlined ahead of the weekend. Nodes enforcing BIP-110 began rejecting blocks that did not signal support through bit 4, running from block 961,632 through block 963,647, with lock-in no later than block 963,648.
With the overwhelming majority of mining power behind the main chain, the BIP-110 branch produced only two blocks before ceasing to advance. The bitcoin.org BIP-110 page was updated to reflect the proposal’s Closed status as of version 1.0.1, dated 9 August 2026, following the stalled split.
Under BIP-110’s deployment state machine, there is no FAILED state: the timeout is disabled, and EXPIRED is the terminal condition. Miner signalling after expiry has no effect, because the deployment is no longer in the STARTED state.
The data restrictions that motivated the whole exercise, if they had locked in, would have lifted automatically after 52,416 blocks, roughly one year, confirming the temporary nature of the soft fork.
The Longer Game: Opposition, Precedent, and What Comes Next
Blockstream co-founder Adam Back and Strategy founder Michael Saylor both opposed BIP-110. Strategy’s public response described the proposal as a consensus change born from a dispute over spam and warned it would set a dangerous precedent. Saylor argued the proposal would begin filtering fee-paying transactions that are currently valid under Bitcoin’s rules.
The Bitcoin Foundation noted that BIP-110 used a 55% activation threshold, below the 95% threshold traditionally used for permanent consensus changes. Critics framed the lower bar as insufficient for a protocol-level rule change affecting which transactions miners can include.
Luke Dashjr, credited as the original adviser on the BIP-110 specification authored by Dathon Ohm, continued to support the proposal throughout. His argument: non-payment data inflates storage costs for full-node operators and dilutes Bitcoin’s monetary purpose.
With the BIP-110 branch effectively dead after two blocks and the specification now Closed, attention shifts to whether a stricter successor emerges. Some BIP-110 supporters have pointed toward a follow-on concept informally called ‘The Cat.’ Whether that gains traction depends on whether the ordinals and inscription debate reignites enough miner and developer interest for another activation attempt.
