Bitcoin's blockchain fractured into two competing versions this week as the BIP-110 activation period went live. The split became visible at block 961632, mined by Antpool, with the BIP-110 supporter group Roughnecks producing a rival version of the same block. Monitoring sites such as forkwatch.tv are now tracking the two chains separately.
Two blocks, one number
At the center of the fracture is block 961632. Antpool mined the version that keeps the legacy rules, while Roughnecks put out an alternative block carrying the BIP-110 changes. Both carry the same height, which is exactly what a chain split looks like — two competing histories from the same point.
The Roughnecks version isn't just a different block. It's a full alternative chain that BIP-110 supporters are treating as the real Bitcoin. The legacy chain, backed by miners like Antpool, continues under the old rules. For now, neither side has budged.
Who's pushing BIP-110
Roughnecks is the group behind the BIP-110 push. Their rival block is a direct challenge to the status quo, and it's the clearest signal yet that they're willing to build a parallel chain to get what they want. Antpool, by contrast, is holding the line on the current consensus rules.
The standoff isn't theoretical anymore. Both blocks exist, both have miners building on them, and both are being tracked by outside observers. That's the difference between a proposal and an actual fork.
What users are seeing
For the average Bitcoin user, the immediate effect depends on which chain they're following. Wallets and exchanges that recognize the legacy chain will show one history. Those that pick up the BIP-110 chain will show another. The two ledgers will diverge more with every new block.
Forkwatch.tv and similar trackers are now the go-to for figuring out which chain is ahead. The sites are updating in real time, showing block counts and miner activity on both sides. It's messy, and it's exactly what a contested upgrade looks like when it stops being a debate.
What the split means
The activation period going live doesn't mean BIP-110 has won. It means the network is now in a state where both rule sets are being mined simultaneously. The longer this goes on, the more the two chains diverge — and the harder it becomes to pretend this is a minor disagreement.
The next thing to watch is whether Roughnecks can attract enough hash rate to make their chain competitive. If they can't, the BIP-110 chain will crawl while the legacy chain moves on. If they do, the split becomes a genuine two-chain race with real economic consequences for anyone holding bitcoin during the transition.
