The proposed Bitcoin Improvement Proposal BIP-110 has stalled after miners overwhelmingly declined to support the initiative over the weekend, causing a brief but quickly halted chain split.
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AAPLChain split and miner response
The split began at block 961,632, triggered when the mandatory signaling window for BIP-110 opened. At that point, nodes running the BIP-110 upgrade started rejecting any block not signaling support through version bit 4. As soon as a non-signaling block was mined, those nodes diverged, forming a separate chain.
However, progress on this BIP-110 chain quickly stalled. The pseudonymous mining group Roughnecks produced both blocks at heights 961,632 and 961,633, utilizing the DATUM protocol from Ocean Mining. After these two blocks, mining activity halted on the forked chain. By Sunday afternoon, the BIP-110 chain was stuck at block 961,633, while the main Bitcoin chain continued to block 961,744—a gap of 111 blocks over about 17 hours.
Support for BIP-110 within the mining community remained minimal. Out of the 2,016 blocks in the previous difficulty adjustment period, only 51 blocks signaled for BIP-110, amounting to just 2.53%. This figure fell far short of the proposal’s 55% threshold required for voluntary lock-in. During the mandatory window, none of the first 113 blocks on the main chain signaled for BIP-110.
| Chain | Latest Block Height | Number of Signaling Blocks (Prior Period) | Support Threshold Needed |
|---|---|---|---|
| Main Bitcoin chain | 961,744 | 51 | 55% |
| BIP-110 fork | 961,633 | 51 | 55% |
Technical hurdles and proposal details
The attempted fork faced additional difficulty due to the way Bitcoin’s proof-of-work mechanism operates. Because the BIP-110 chain inherited the same mining difficulty as the main chain, but held only a negligible portion of the overall hashpower, mining on the forked chain became nearly impossible. The protocol requires completion of an entire 2,016-block period before a new difficulty adjustment can occur. Estimates on how long it might take for the forked chain to reach this point ranged widely from less than a year to multiple decades, depending on how much mining power shifts over.
BIP-110, known formally as the Reduced Data Temporary Softfork, aimed to cap arbitrary data in Bitcoin transactions for approximately one year. The measure targeted the growing use of Ordinals inscriptions and large OP_RETURN payloads, which allow users to embed non-financial data into the blockchain.
Mini dictionary: Ordinals inscriptions, a relatively recent trend on the Bitcoin network, enable users to inscribe arbitrary data such as images and text onto individual satoshis, the smallest unit of Bitcoin. This has sparked debate due to its impact on network congestion and block size.
Industry reaction and miner reimbursements
Prominent industry figures expressed opposition to BIP-110 and its activation method. MicroStrategy co-founder Michael Saylor and Blockstream CEO Adam Back both raised concerns about the process, suggesting the approach risked causing precisely the type of chain split that occurred. Saylor argued that Bitcoin’s consensus mechanism had functioned as intended, keeping 99.85% of hashpower on the main chain.
Michael Saylor said Bitcoin continued to operate as designed, with the overwhelming majority of miners—99.85%—remaining on the dominant chain during the chain split event.
Ocean Mining, a company that supported the BIP-110 initiative, notified clients that some miners using its Stratum templates may have unknowingly contributed their hashpower to the new fork, believing they were supporting the original Bitcoin chain. Ocean committed to reimbursing affected miners with the rewards they would have received if they had continued mining on the main chain during the relevant period.
Ocean Mining stated it would compensate any miners impacted by the hashpower redirection to the BIP-110 fork, ensuring they receive the block rewards they would have earned on the non-BIP-110 chain during that period.
