XBT history: soft forks, hard forks and the BLAKE2b split
XBT exists because a Bitcoin rule change split the chain in August 2026, and the smaller side then changed its mining algorithm to survive. In three steps:
- A soft fork. Supporters of BIP-110, a proposal to limit non-payment data in Bitcoin transactions, began enforcing it at block 961,632 on August 8, 2026.
- A split. Almost all miners kept the old rules, so the chain divided in two. The BIP-110 side had very little hashpower and nearly stopped.
- A hard fork. On August 30, the BIP-110 chain replaced Bitcoin's SHA-256 mining with BLAKE2b. That chain is XBT, also listed as BTCB2.
Soft forks and hard forks, in plain English
A blockchain is a list of rules that every node checks. Changing those rules is called a fork. There are two kinds.
| Soft fork | Hard fork | |
|---|---|---|
| What changes | Rules get stricter. Some blocks that were valid become invalid. | Rules get looser or different. Blocks valid under the new rules are invalid under the old ones. |
| Old nodes | Keep following the chain without upgrading, as long as most miners enforce the new rules. | Reject the new blocks. Everyone has to upgrade or end up on a different chain. |
| Risk of a split | Low with majority miner support. High without it. | A split is certain unless almost everyone upgrades. |
| Bitcoin examples | P2SH (2012), SegWit (2017), Taproot (2021) | Bitcoin Cash (2017, bigger blocks) |
| XBT examples | BIP-110 (Aug 2026), the 45-day coinbase lock | The BLAKE2b proof-of-work change (Aug 30, 2026) |
The key point: a soft fork only stays one chain if most miners enforce it. When a minority enforces a soft fork, it behaves like a hard fork, and the chain splits. That is what happened to BIP-110.
Bitcoin's forks at a glance
Bitcoin has changed its rules many times. Most changes were soft forks, and the method for turning them on has shifted over the years, from simply shipping new rules, to miner signaling thresholds, to activation pushed by node operators.
| When | Change | Type | How it was turned on |
|---|---|---|---|
| 2010 | 1 MB block size limit | Soft fork | Shipped in node software, no signaling |
| Aug 2010 | Value overflow bug fix (184 billion BTC created) | Soft fork | Emergency patch; the bad block was orphaned |
| Apr 2012 | P2SH (BIP16) | Soft fork | Miner signaling, 55% threshold |
| Mar 2013 | Block height in coinbase (BIP34) | Soft fork | Miner signaling, 75% / 95% |
| Mar to May 2013 | Accidental split from a database limit (BIP50) | Split, then hard fork | Miners reverted to old software, then the limit was removed |
| 2015 | Strict signatures (BIP66), CheckLockTimeVerify (BIP65) | Soft forks | Miner signaling |
| Jul 2016 | Relative lock time (BIPs 68, 112, 113) | Soft fork | Miner signaling, 95% (BIP9) |
| Aug 2017 | SegWit (BIP141) | Soft fork | Miner signaling (BIP91) under pressure from a user-activated soft fork (BIP148) |
| Aug 2017 | Bitcoin Cash | Hard fork (split) | Bigger-block supporters left with a new chain |
| Nov 2021 | Taproot (BIPs 340 to 342) | Soft fork | Miner signaling, 90% ("Speedy Trial") |
| Aug 2026 | BIP-110 data limits | Soft fork, enforced by a minority | Mandatory signaling from block 961,632; most miners declined, so the chain split |
| Aug 2026 | BLAKE2b proof of work (XBT chain only) | Hard fork | New node software (Knots 29.4.1) at block 961,640 |
Classifications vary. Some developers, including Luke Dashjr in a July 28, 2026 post on X, argue that every soft fork is ultimately enforced by users rather than miners and label several of these differently, for example SegWit as user-activated.
Why BIP-110 was proposed
From 2023 on, inscriptions and other ways of storing images and data in Bitcoin blocks became popular. Some users and node operators, many running Bitcoin Knots, saw this as spam that crowds out payments and grows the chain. Others, including most Bitcoin Core developers, argued that fees decide what goes in a block and that filtering only pushes data elsewhere. The debate sharpened when Bitcoin Core relaxed its default limit on data in OP_RETURN outputs in 2025.
BIP-110 was the filtering side's answer: a temporary soft fork that caps the size of data fields in transactions, with existing coins exempt. It was assigned its number in December 2025 and set to require miner signaling from block 961,632.
Timeline
| When | What happened |
|---|---|
| Dec 2025 | BIP-110 is assigned its number. Mandatory signaling is scheduled to start at block 961,632. |
| Early Aug 2026 | Miner signaling for BIP-110 peaks around 2.5% of blocks, far short of a majority. |
| Aug 8, 2026 | Block 961,632: the chain splits. AntPool mines the first block without BIP-110 signaling and OCEAN mines a BIP-110 block. Nearly all hashpower stays on the old rules. The BIP-110 chain finds two blocks in about 8 hours. At that hashpower, its next difficulty adjustment was roughly 350 days away. |
| Aug 30, 2026 | Block 961,640: the BLAKE2b hard fork. Bitcoin Knots 29.4.1 switches the BIP-110 chain from SHA-256 to BLAKE2b proof of work. SHA-256 miners can no longer mine it, and BLAKE2b ASICs, built for other coins, can. |
| Sep 1, 2026 | Trading opens on NeoxEX. Listing-day prints on an empty order book are wild. |
| Sep 5, 2026 | All-time high of $1,799, followed by a drop of more than 80% within days. |
| Sep 8, 2026 | AlphaPool briefly finds more than 50% of blocks, then caps itself at 30%. NeoxEX lists the coin as XBT. About 27 pools are now mining at around 17 PH/s. |
| Mid Sep 2026 | Block 973,440: the 45-day coinbase lock window begins (see below). |
| Early Oct 2026 | Hash rate passes 45 PH/s. No single pool holds a majority. |
| Early Nov 2026 | Block 979,920: locked block rewards start unlocking, about 450 XBT a day for 45 days. |
Why change the mining algorithm?
A chain with almost no hashpower is stuck: blocks come hours or days apart, and difficulty takes months to adjust down. It is also defenseless, because any large SHA-256 miner could overpower it in minutes.
Switching to BLAKE2b fixed both problems at once. Difficulty reset to fit the miners actually present, and the huge SHA-256 mining industry could no longer touch the chain. The trade-off is that XBT now depends on a much smaller pool of BLAKE2b hardware, mostly machines originally built for other coins.
The 45-day coinbase lock: a soft fork inside XBT
XBT has already used a soft fork of its own. Block rewards mined from block 973,440 to 979,920 cannot be spent until 6,480 blocks after they were mined, about 45 days. Because the rule only makes things stricter, nodes and wallets did not need a hard fork to adopt it. The rewards unlock one block at a time from block 979,920 to 986,400. Live countdown on the unlock page.
What carried over from Bitcoin
- History and balances. XBT shares Bitcoin's full transaction history up to the split. Keys that held bitcoin before August 8, 2026 hold the same amount of XBT.
- Supply schedule. Same 21 million cap and same halving schedule. The block reward is 3.125 XBT, and the next halving is at block 1,050,000.
- What changed. The mining algorithm (BLAKE2b instead of SHA-256), the BIP-110 data limits, and a much smaller set of miners, pools and exchanges.
Held bitcoin before the split? Read the FAQ steps before moving those coins on either chain.
Names: XBT, BTCB2, Bitcoin BLAKE2b
They are the same coin. BTCB2 and Bitcoin BLAKE2b are the original names. NeoxEX began listing it as XBT on September 8, 2026, and the name stuck with much of the community, although XBT has also long been used as a code for bitcoin itself. Some venues still list it as BTCB2.
Two views
Supporters see XBT as Bitcoin's monetary rules without what they consider spam, with mining reset away from today's largest SHA-256 operators. Critics see a minority chain that split from Bitcoin over a policy disagreement, with thin markets and a small mining base. Both views are common, and this site doesn't pick a side. It tracks the data.
Dates and block heights are from block explorers and contemporary reporting, including CoinDesk (Aug 9, 2026) and news.bitcoin.com (Sep 8, 2026). Spot an error? Tell us on X @Xbt_Live.
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