{ "$schema": "https://degreesofsatoshi.com/encyclopedia/schemas/article-v1.json", "schemaVersion": "1.0.0", "id": "bitcoin-cash-fork-2017", "canonical": "https://degreesofsatoshi.com/encyclopedia/bitcoin-cash-fork-2017/", "collection": "bitcoin", "title": "Bitcoin Cash: why Bitcoin split on 1 August 2017, and what happened to both sides after", "description": "Bitcoin Cash’s 2017 split: shared earlier history, incompatible block rules and replay protection. Distinguish the historical fork from current network settings.", "aliases": [ "Bitcoin Cash fork", "Bitcoin Cash 2017", "why did Bitcoin split", "Bitcoin vs Bitcoin Cash", "Bitcoin Cash hard fork", "Bitcoin SV split", "UAHF" ], "dates": { "published": "2026-09-23", "modified": "2026-10-02", "verified": "2026-10-02T18:22:07.965Z", "dataAsOf": null }, "authorship": { "publisher": "Degrees of Satoshi editorial project", "process": "AI-assisted research and drafting with a separate automated source-verification pass; no external expert or named human review is implied." }, "quickAnswer": { "text": "Bitcoin Cash is a separate cryptocurrency created by an incompatible rule change in August 2017. Its initial specification required larger-block support, omitted SegWit and added replay-protection rules. It shares Bitcoin’s earlier history through block 478,558, after which separate histories developed. The November 2018 Bitcoin Cash dispute produced another persistent split, including Bitcoin SV.", "claimId": "bitcoin-cash-fork-2017-quick-answer", "sourceIds": [ "uahf-spec", "irs-cca", "coindesk-bsv-split" ] }, "keyFacts": [ { "label": "Split", "value": "Shared history through block 478,558; the first distinct Bitcoin Cash block is 478,559", "sourceIds": [ "irs-cca", "coindesk-first-block" ], "id": "split", "claimId": "bitcoin-cash-fork-2017-fact-split" }, { "label": "Fork trigger", "value": "Activation was specified using median time past of at least Unix time 1501590000 (1 August 2017, 12:20 UTC), not a guaranteed wall-clock block time", "sourceIds": [ "uahf-spec" ], "id": "fork-trigger", "claimId": "bitcoin-cash-fork-2017-fact-fork-trigger" }, { "label": "First Bitcoin Cash block", "value": "Mined by ViaBTC at about 6:14 p.m. UTC; 1.915 MB; 6,985 transactions", "sourceIds": [ "coindesk-first-block" ], "id": "first-bitcoin-cash-block", "claimId": "bitcoin-cash-fork-2017-fact-first-bitcoin-cash-block" }, { "label": "Block size", "value": "The cited UAHF specification required the configured acceptance limit to be at least 8,000,000 bytes; the first fork block itself had to exceed 1,000,000 bytes", "sourceIds": [ "uahf-spec" ], "id": "block-size", "claimId": "bitcoin-cash-fork-2017-fact-block-size" }, { "label": "SegWit", "value": "Not included", "sourceIds": [ "uahf-spec", "coindesk-why-forking" ], "id": "segwit", "claimId": "bitcoin-cash-fork-2017-fact-segwit" }, { "label": "Replay protection", "value": "A new signature flag, SIGHASH_FORKID", "sourceIds": [ "uahf-spec" ], "id": "replay-protection", "claimId": "bitcoin-cash-fork-2017-fact-replay-protection" }, { "label": "Origin", "value": "Bitmain’s UAHF contingency plan, published 14 June 2017", "sourceIds": [ "bitmain-reporting" ], "id": "origin", "claimId": "bitcoin-cash-fork-2017-fact-origin" }, { "label": "Second split", "value": "Bitcoin SV, 15 November 2018, after block 556,766", "sourceIds": [ "coindesk-bsv-split", "bch-nov-2018-spec" ], "id": "second-split", "claimId": "bitcoin-cash-fork-2017-fact-second-split" } ], "prerequisites": [], "sections": [ { "id": "two-answers", "heading": "Two answers to one question: how should Bitcoin carry more payments?", "sourceIds": [ "bitcoincash-org", "coindesk-why-forking", "uahf-spec" ], "paragraphs": [ "By 2017 Bitcoin’s blocks were often full. A block could hold about 1 MB of transactions, and when demand exceeded that, people paid more to get in and waited longer if they did not. Nobody disputed the problem. The dispute was about the fix, and it ran for years before it came to a head. Our [block size war dossier](/history/bitcoin-block-size-war/) reconstructs that history from the proposals, software releases and block records; this article is about the split it produced.", "One camp wanted to keep the base layer small enough that ordinary people could run a node, and to grow capacity with SegWit, a soft fork that discounts signature data and fixes an old bug, plus payment systems built on top. The other camp wanted to raise the block size limit directly, which requires a hard fork: a rule change that older software rejects, so everyone must upgrade or split. Bitcoin Cash’s own website describes the divide the same way: “One side favored keeping blocks small and positioning Bitcoin as a settlement layer. The other believed in scaling on-chain to preserve its utility as everyday electronic cash.”", "Both positions were held sincerely by people who had been in Bitcoin for years. If you are new to the vocabulary, our article on [soft forks and hard forks](/encyclopedia/soft-forks-and-hard-forks/) explains why one kind of change can be rolled out gradually and the other cannot." ] }, { "id": "contingency-plan", "heading": "It started as a contingency plan", "sourceIds": [ "bitmain-reporting", "coindesk-why-forking" ], "paragraphs": [ "The immediate trigger was a deadline. A proposal called BIP148 would have had nodes reject any block that did not signal for SegWit from 1 August 2017, a tactic known as a user-activated soft fork. On 14 June 2017, Bitcoin Magazine reported, the mining hardware company Bitmain published a plan for a user-activated hard fork, or UAHF, with blocks of up to 8 MB. Bitmain framed it as insurance rather than a project: the UAHF “will only be launched in response to a successful BIP148 UASF.”", "It became a project anyway. A software implementation called Bitcoin ABC adopted the UAHF rules, and in late July the mining pool ViaBTC said it would list the resulting coin under the name Bitcoin Cash. CoinDesk’s report from 26 July 2017 described the plan as two main changes, an 8 MB block size and the removal of SegWit, and set the time: 1 August at 12:20 UTC. One developer quoted in that report, Calin Culianu, tied it to the separate SegWit2x compromise, predicting that if that agreement’s promised block size increase failed to materialize, “many miners will likely defect to Bitcoin Cash.”" ] }, { "id": "what-changed", "heading": "What changed in the code", "sourceIds": [ "uahf-spec" ], "paragraphs": [ "The technical specification published by the Bitcoin Cash project is short and specific. The fork was time-based: it triggered when the median timestamp of the last eleven blocks passed 1501590000, which the document translates as 1 August 2017 at 12:20 UTC. Blocks up to 1,000,000 bytes stayed under the old rules. Above that, the software required the operator to allow at least 8,000,000 bytes, with the rationale that “8MB is chosen as a minimum since miners have indicated in the past that they would be willing to support such a size.”", "Two details made the split clean. First, the specification required the very first post-fork block to be larger than 1 MB, so that Bitcoin nodes would reject it and the two chains could not accidentally rejoin. Second, it changed how transactions are signed, adding a flag called SIGHASH_FORKID, so a transaction valid on one chain would be invalid on the other. Without that replay protection, a payment on one chain could be copied onto the other by anyone who saw it.", "SegWit was simply absent. The signing changes are described as an adaptation for a “non-Segwit deployment,” and none of the SegWit rules were carried over. That absence is what made Bitcoin Cash a different network rather than a variant: Bitcoin went on to activate [SegWit](/encyclopedia/segwit-explained/) later that month, and from then on the two chains accepted different transactions and different blocks." ] }, { "id": "the-split", "heading": "1 August 2017: the ledger splits at block 478,558", "sourceIds": [ "irs-cca", "coindesk-first-block", "coindesk-why-forking" ], "paragraphs": [ "The split has an unusually official description. In a memorandum on how to tax forked coins, the IRS Office of Chief Counsel wrote: “On August 1, 2017, at block height 478,558, the bitcoin ledger split into two separate ledgers. Bitcoin Cash became available and tradeable on cryptocurrency exchanges shortly after the fork occurred.” Every coin that existed at that height existed on both chains, so anyone holding bitcoin then also held the same amount of Bitcoin Cash, whether or not their wallet or exchange let them reach it.", "Then, for several hours, nothing. The fork time passed at 12:20 UTC, but a chain needs a block, and mining one at Bitcoin’s difficulty with a small share of the hash power takes time. CoinDesk reported that ViaBTC mined the first Bitcoin Cash block at about 6:14 p.m. UTC, nearly six hours later. It was 1.915 MB and held 6,985 transactions, which made the point: it was a block Bitcoin’s rules would never have accepted.", "From that block on there were two networks, two coins and two communities, each convinced the other had left. Bitcoin kept its name and ticker; Bitcoin Cash kept the shared history up to the split and set its own rules from there." ] }, { "id": "bitcoin-sv", "heading": "Bitcoin Cash splits again: Bitcoin SV, November 2018", "sourceIds": [ "bch-nov-2018-spec", "coindesk-bsv-split" ], "paragraphs": [ "Bitcoin Cash scheduled regular upgrades, and the one due on 15 November 2018 broke its community in two. The Bitcoin ABC side’s specification for that date added a new opcode, OP_CHECKDATASIG, required transactions within a block to be sorted in numerical order, and set a minimum transaction size of 100 bytes. It said nothing about the block size, which by then stood at 32 MB.", "A rival implementation, Bitcoin SV, short for Satoshi’s Vision, rejected those changes. CoinDesk reported that it aimed instead to “restore retired code from the original bitcoin protocol” and to raise the block size “from 32 MB to 128 MB.” Its most prominent public supporter, CoinDesk reported, was Craig Wright, the subject of our article on the [COPA ruling](/encyclopedia/craig-wright-copa-ruling/). In the days before the fork, mining pools supporting Bitcoin SV held a majority of Bitcoin Cash’s hash power, and there was open talk of a “hash war” in which each side would try to out-mine or disrupt the other.", "The chain split on 15 November 2018 after block 556,766, the last block the two sides shared. Neither side eliminated the other. Bitcoin Cash continued under the ABC rules and Bitcoin SV continued as its own network. That is the recurring lesson of 2017 and 2018: when people who disagree about the rules cannot persuade each other, the system lets them separate rather than forcing one answer on everyone." ] }, { "id": "what-it-settled", "heading": "What the fork settled, and what it did not", "sourceIds": [ "irs-cca", "uahf-spec", "coindesk-bsv-split" ], "paragraphs": [ "The split answered one question for good: a hard fork with replay protection can create a working second chain without breaking the first. Holders ended up with coins on both. Exchanges, wallets and tax authorities had to decide how to treat the new asset, and the IRS memorandum quoted above is one result of that.", "It did not settle the argument. Each community believes it kept the real Bitcoin, and no technical fact can adjudicate that; it is a question of which rules people choose to run and which coin they choose to value. What the record shows is narrower and more useful. Bitcoin’s rules were not changed by the fork. Bitcoin Cash’s rules did change, first to 8 MB blocks and then further, and its own disagreements produced a second split a little over fifteen months later. Both outcomes came from the same mechanism, people running the software they preferred, which is the part of the story that our [block size war dossier](/history/bitcoin-block-size-war/) is really about." ] }, { "id": "reading-the-evidence", "heading": "Separate the 2017 fork rules from present-day product claims", "sourceIds": [ "uahf-spec", "bch-nov-2018-spec" ], "paragraphs": [ "A historical fork specification answers which rules separated the networks at that point. It should not be used as a current specification for either network after later upgrades. Read the date and activation conditions before repeating a block-size or signing rule.", "Replay protection addresses a narrower issue than wallet access: whether a signature intended for one branch can be reused as a valid spend on the other. It does not by itself establish that a custodian credited a customer, that a wallet supports both branches, or that a person can spend an output without satisfying its locking conditions." ] } ], "faq": [ { "question": "Is Bitcoin Cash the same as Bitcoin?", "answer": "No. They share a transaction history up to block 478,558 on 1 August 2017 and have been separate networks with separate coins since. Bitcoin Cash uses larger blocks, does not include SegWit, and signs transactions differently so payments cannot be replayed between the two chains.", "sourceIds": [ "irs-cca", "uahf-spec" ] }, { "question": "Did people who held bitcoin get Bitcoin Cash?", "answer": "The chains shared the ledger state at the split, so the pre-fork unspent outputs were represented on both branches. A person able to satisfy an output’s spending conditions could potentially spend on each chain under its rules. Customers of a custodian depended on that service’s access and crediting policy; a Bitcoin account balance did not itself guarantee access to Bitcoin Cash.", "sourceIds": [ "irs-cca", "coindesk-why-forking" ] }, { "question": "Why did Bitcoin Cash reject SegWit?", "answer": "Its supporters wanted capacity to come from bigger blocks on the base chain rather than from a signature discount and second-layer systems. The fork specification was written as a non-SegWit deployment, and contemporaneous reporting described the removal of SegWit as one of its two defining changes.", "sourceIds": [ "uahf-spec", "coindesk-why-forking", "bitcoincash-org" ] }, { "question": "What is Bitcoin SV?", "answer": "Bitcoin SV, short for Satoshi’s Vision, is the chain that split from Bitcoin Cash on 15 November 2018 after block 556,766. Its backers rejected the Bitcoin ABC upgrade and wanted a 128 MB block size and the return of retired opcodes. Both chains continued after a much-anticipated hash war failed to eliminate either.", "sourceIds": [ "coindesk-bsv-split", "bch-nov-2018-spec" ] } ], "claims": [ { "id": "bitcoin-cash-fork-2017-quick-answer", "articleSlug": "bitcoin-cash-fork-2017", "statement": "Bitcoin Cash is a separate cryptocurrency created by an incompatible rule change in August 2017. Its initial specification required larger-block support, omitted SegWit and added replay-protection rules. It shares Bitcoin’s earlier history through block 478,558, after which separate histories developed. The November 2018 Bitcoin Cash dispute produced another persistent split, including Bitcoin SV.", "sourceIds": [ "source-565c71046e083d3d", "source-aeb722c1b6a5670e", "source-e3348a71ad522779" ], "sourceLocators": [ { "sourceId": "source-565c71046e083d3d", "locator": "The fork rules: activation at median time past 1501590000 (1 August 2017, 12:20 UTC), an 8 MB minimum block size, a first fork block over 1 MB, SIGHASH_FORKID replay protection, and signing adapted for a non-SegWit deployment." }, { "sourceId": "source-aeb722c1b6a5670e", "locator": "An official record stating that on 1 August 2017, at block height 478,558, the bitcoin ledger split into two ledgers and Bitcoin Cash became tradeable shortly after." }, { "sourceId": "source-e3348a71ad522779", "locator": "Reports the 15 November 2018 split after block 556,766, Bitcoin SV’s aim of restoring retired code and raising blocks from 32 MB to 128 MB, Craig Wright’s support, and the pre-fork hash power picture." } ], "scope": { "collection": "bitcoin", "dataAsOf": null, "blockHeight": null }, "qualification": "", "evidenceStatus": "documented", "verification": { "status": "verified", "method": "independent automated source review", "checkedAt": "2026-10-02T18:22:07.965Z", "reviewer": "automated independent verification agent /root/content_seo_verification", "notes": [ "Read the pinned UAHF replay-protection specification and 2018 upgrade scope. Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. Final FAQ distinguishes controlling spending conditions from a custodian customer’s access/crediting policy; no tax conclusion is added." ] } }, { "id": "bitcoin-cash-fork-2017-fact-split", "articleSlug": "bitcoin-cash-fork-2017", "statement": "Split: Shared history through block 478,558; the first distinct Bitcoin Cash block is 478,559", "sourceIds": [ "source-aeb722c1b6a5670e", "source-54902ec07d30f67e" ], "sourceLocators": [ { "sourceId": "source-aeb722c1b6a5670e", "locator": "An official record stating that on 1 August 2017, at block height 478,558, the bitcoin ledger split into two ledgers and Bitcoin Cash became tradeable shortly after." }, { "sourceId": "source-54902ec07d30f67e", "locator": "Reports the first Bitcoin Cash block mined by ViaBTC at about 6:14 p.m. UTC, nearly six hours after block 478,558, at 1.915 MB with 6,985 transactions." } ], "scope": { "collection": "bitcoin", "dataAsOf": null, "blockHeight": null }, "qualification": "", "evidenceStatus": "documented", "verification": { "status": "verified", "method": "independent automated source review", "checkedAt": "2026-10-02T18:22:07.965Z", "reviewer": "automated independent verification agent /root/content_seo_verification", "notes": [ "Read the pinned UAHF replay-protection specification and 2018 upgrade scope. Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. 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Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. Final FAQ distinguishes controlling spending conditions from a custodian customer’s access/crediting policy; no tax conclusion is added." ] } }, { "id": "bitcoin-cash-fork-2017-fact-first-bitcoin-cash-block", "articleSlug": "bitcoin-cash-fork-2017", "statement": "First Bitcoin Cash block: Mined by ViaBTC at about 6:14 p.m. UTC; 1.915 MB; 6,985 transactions", "sourceIds": [ "source-54902ec07d30f67e" ], "sourceLocators": [ { "sourceId": "source-54902ec07d30f67e", "locator": "Reports the first Bitcoin Cash block mined by ViaBTC at about 6:14 p.m. UTC, nearly six hours after block 478,558, at 1.915 MB with 6,985 transactions." } ], "scope": { "collection": "bitcoin", "dataAsOf": null, "blockHeight": null }, "qualification": "", "evidenceStatus": "documented", "verification": { "status": "verified", "method": "independent automated source review", "checkedAt": "2026-10-02T18:22:07.965Z", "reviewer": "automated independent verification agent /root/content_seo_verification", "notes": [ "Read the pinned UAHF replay-protection specification and 2018 upgrade scope. Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. Final FAQ distinguishes controlling spending conditions from a custodian customer’s access/crediting policy; no tax conclusion is added." ] } }, { "id": "bitcoin-cash-fork-2017-fact-block-size", "articleSlug": "bitcoin-cash-fork-2017", "statement": "Block size: The cited UAHF specification required the configured acceptance limit to be at least 8,000,000 bytes; the first fork block itself had to exceed 1,000,000 bytes", "sourceIds": [ "source-565c71046e083d3d" ], "sourceLocators": [ { "sourceId": "source-565c71046e083d3d", "locator": "The fork rules: activation at median time past 1501590000 (1 August 2017, 12:20 UTC), an 8 MB minimum block size, a first fork block over 1 MB, SIGHASH_FORKID replay protection, and signing adapted for a non-SegWit deployment." } ], "scope": { "collection": "bitcoin", "dataAsOf": null, "blockHeight": null }, "qualification": "", "evidenceStatus": "documented", "verification": { "status": "verified", "method": "independent automated source review", "checkedAt": "2026-10-02T18:22:07.965Z", "reviewer": "automated independent verification agent /root/content_seo_verification", "notes": [ "Read the pinned UAHF replay-protection specification and 2018 upgrade scope. Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. Final FAQ distinguishes controlling spending conditions from a custodian customer’s access/crediting policy; no tax conclusion is added." ] } }, { "id": "bitcoin-cash-fork-2017-fact-segwit", "articleSlug": "bitcoin-cash-fork-2017", "statement": "SegWit: Not included", "sourceIds": [ "source-565c71046e083d3d", "source-f33ce7d36caff728" ], "sourceLocators": [ { "sourceId": "source-565c71046e083d3d", "locator": "The fork rules: activation at median time past 1501590000 (1 August 2017, 12:20 UTC), an 8 MB minimum block size, a first fork block over 1 MB, SIGHASH_FORKID replay protection, and signing adapted for a non-SegWit deployment." }, { "sourceId": "source-f33ce7d36caff728", "locator": "Contemporaneous reporting describing the two main changes (8 MB blocks and no SegWit), the roles of Bitcoin ABC, ViaBTC and Bitmain, the 12:20 UTC fork time, and the Culianu quote about SegWit2x." } ], "scope": { "collection": "bitcoin", "dataAsOf": null, "blockHeight": null }, "qualification": "", "evidenceStatus": "documented", "verification": { "status": "verified", "method": "independent automated source review", "checkedAt": "2026-10-02T18:22:07.965Z", "reviewer": "automated independent verification agent /root/content_seo_verification", "notes": [ "Read the pinned UAHF replay-protection specification and 2018 upgrade scope. Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. 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Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. 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Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. 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Checked the IRS memorandum’s shared-ledger and hosted-wallet scenarios solely for historical access distinctions. Final FAQ distinguishes controlling spending conditions from a custodian customer’s access/crediting policy; no tax conclusion is added." ] } } ], "sources": [ { "id": "uahf-spec", "label": "UAHF Technical Specification", "publisher": "bitcoincash.org repository on GitHub", "url": "https://raw.githubusercontent.com/bitcoincashorg/bitcoincash.org/3e2e6da8c38dab7ba12149d327bc4b259aaad684/spec/uahf-technical-spec.md", "note": "The fork rules: activation at median time past 1501590000 (1 August 2017, 12:20 UTC), an 8 MB minimum block size, a first fork block over 1 MB, SIGHASH_FORKID replay protection, and signing adapted for a non-SegWit deployment.", "checkedAt": "2026-10-02T15:04:18.120183+00:00", "contentSha256": "459652647bcf38f92305a93b98e24cb1c827fab83186065f6e4b71b2ac11078a", "version": "3e2e6da8c38dab7ba12149d327bc4b259aaad684", "locator": "The fork rules: activation at median time past 1501590000 (1 August 2017, 12:20 UTC), an 8 MB minimum block size, a first fork block over 1 MB, SIGHASH_FORKID replay protection, and signing adapted for a non-SegWit deployment.", "recordId": "source-565c71046e083d3d" }, { "id": "bitmain-reporting", "label": "Bitmain Responds to UASF With Another Bitcoin Hard Fork Announcement", "publisher": "Bitcoin Magazine", "author": "Aaron van Wirdum", "issued": "2017-06-14", "url": "https://bitcoinmagazine.com/technical/bitmain-responds-uasf-another-hard-fork-announcement", "note": "Reporting on Bitmain’s 14 June 2017 UAHF plan, including the up-to-8 MB block size and the statement that it would only launch in response to a successful BIP148; Bitmain’s original blog post is no longer reachable.", "checkedAt": "2026-10-02T14:48:58.086015+00:00", "contentSha256": "8c4e11d18f9a520eaa6ccb8b9b1755541bb145db6af3fed13597a77145799a4c", "locator": "Reporting on Bitmain’s 14 June 2017 UAHF plan, including the up-to-8 MB block size and the statement that it would only launch in response to a successful BIP148; Bitmain’s original blog post is no longer reachable.", "recordId": "source-1970d9b8a81f2da6", "version": null }, { "id": "coindesk-why-forking", "label": "Bitcoin Cash: Why It’s Forking the Blockchain and What That Means", "publisher": "CoinDesk", "author": "Alyssa Hertig", "issued": "2017-07-26", "url": "https://www.coindesk.com/markets/2017/07/26/bitcoin-cash-why-its-forking-the-blockchain-and-what-that-means", "note": "Contemporaneous reporting describing the two main changes (8 MB blocks and no SegWit), the roles of Bitcoin ABC, ViaBTC and Bitmain, the 12:20 UTC fork time, and the Culianu quote about SegWit2x.", "checkedAt": "2026-10-02T14:48:59.586328+00:00", "contentSha256": "e2c4b6d653928b8403b2ba4b97a56e7925ee02535ce607ae41d9f62c78aecb4e", "locator": "Contemporaneous reporting describing the two main changes (8 MB blocks and no SegWit), the roles of Bitcoin ABC, ViaBTC and Bitmain, the 12:20 UTC fork time, and the Culianu quote about SegWit2x.", "recordId": "source-f33ce7d36caff728", "version": null }, { "id": "coindesk-first-block", "label": "Bitcoin Cash Just Mined Its First Block, Making Blockchain Split Official", "publisher": "CoinDesk", "author": "Stan Higgins", "issued": "2017-08-01", "url": "https://www.coindesk.com/markets/2017/08/01/bitcoin-cash-just-mined-its-first-block-making-blockchain-split-official/", "note": "Reports the first Bitcoin Cash block mined by ViaBTC at about 6:14 p.m. UTC, nearly six hours after block 478,558, at 1.915 MB with 6,985 transactions.", "checkedAt": "2026-10-02T14:48:59.469416+00:00", "contentSha256": "3dc0b20f62c9ceff1bdd16b8a5e5730dfd8a68b709b7ee677ffd5c65fa6844dc", "locator": "Reports the first Bitcoin Cash block mined by ViaBTC at about 6:14 p.m. UTC, nearly six hours after block 478,558, at 1.915 MB with 6,985 transactions.", "recordId": "source-54902ec07d30f67e", "version": null }, { "id": "irs-cca", "label": "Chief Counsel Advice memorandum 202114020", "publisher": "Internal Revenue Service", "url": "https://www.irs.gov/pub/irs-wd/202114020.pdf", "note": "An official record stating that on 1 August 2017, at block height 478,558, the bitcoin ledger split into two ledgers and Bitcoin Cash became tradeable shortly after.", "checkedAt": "2026-10-02T15:04:19.292201+00:00", "contentSha256": "9ef1ce5276c8e3113109c7a18f7fdd3b1090b54c4f74005a13a41064dfb8c22c", "locator": "An official record stating that on 1 August 2017, at block height 478,558, the bitcoin ledger split into two ledgers and Bitcoin Cash became tradeable shortly after.", "recordId": "source-aeb722c1b6a5670e", "version": null }, { "id": "bch-nov-2018-spec", "label": "2018 November Upgrade Specification", "publisher": "bitcoincash.org repository on GitHub", "url": "https://raw.githubusercontent.com/bitcoincashorg/bitcoincash.org/3e2e6da8c38dab7ba12149d327bc4b259aaad684/spec/2018-nov-upgrade.md", "note": "The Bitcoin ABC rules that activated on 15 November 2018: numerically sorted transactions, OP_CHECKDATASIG, a 100-byte minimum transaction size and updated replay protection.", "checkedAt": "2026-10-02T15:04:19.345814+00:00", "contentSha256": "b999b5d8cfa9f753aad9aef76fa3779730abd6a0cce5e2753726b63b4fe0a6ec", "version": "3e2e6da8c38dab7ba12149d327bc4b259aaad684", "locator": "The Bitcoin ABC rules that activated on 15 November 2018: numerically sorted transactions, OP_CHECKDATASIG, a 100-byte minimum transaction size and updated replay protection.", "recordId": "source-71438b844c2c7993" }, { "id": "coindesk-bsv-split", "label": "Bitcoin Cash Just Split Into Two Blockchains", "publisher": "CoinDesk", "author": "Christine Kim", "issued": "2018-11-15", "url": "https://www.coindesk.com/markets/2018/11/15/bitcoin-cash-just-split-into-two-blockchains", "note": "Reports the 15 November 2018 split after block 556,766, Bitcoin SV’s aim of restoring retired code and raising blocks from 32 MB to 128 MB, Craig Wright’s support, and the pre-fork hash power picture.", "checkedAt": "2026-10-02T14:48:59.991761+00:00", "contentSha256": "82804af28ebd9ffea39efe298d2d529b8dd188f592e864088f2238062a94e2f9", "locator": "Reports the 15 November 2018 split after block 556,766, Bitcoin SV’s aim of restoring retired code and raising blocks from 32 MB to 128 MB, Craig Wright’s support, and the pre-fork hash power picture.", "recordId": "source-e3348a71ad522779", "version": null }, { "id": "bitcoincash-org", "label": "Bitcoin Cash: Peer-to-Peer Electronic Cash", "publisher": "bitcoincash.org (the Bitcoin Cash project’s own site)", "url": "https://bitcoincash.org/", "note": "The project’s self-description, including its account of the scaling divide between a settlement-layer view and on-chain scaling for everyday cash.", "checkedAt": "2026-10-02T14:48:58.853587+00:00", "contentSha256": "117adef91c11ff2c77bd4ceb9f160d79930acc1edfc43a2d3894fbd8a1c6a146", "locator": "The project’s self-description, including its account of the scaling divide between a settlement-layer view and on-chain scaling for everyday cash.", "recordId": "source-f6779978246c3027", "version": null } ], "related": { "articles": [ "soft-forks-and-hard-forks", "segwit-explained", "anatomy-of-a-bitcoin-block", "craig-wright-copa-ruling", "bitcoin-transaction-fees-and-mempool" ], "dossiers": [ "bitcoin-block-size-war" ], "wallets": [] }, "revisionHistory": [ { "date": "2026-09-23", "kind": "published", "summary": "Initial Bitcoin encyclopedia entry at this permanent URL." }, { "date": "2026-10-02", "kind": "correction", "summary": "Revised direct answer to preserve source scope and qualifications. Corrected key fact: Split Corrected key fact: Fork trigger Corrected key fact: Block size" }, { "date": "2026-10-02", "kind": "publishing-format", "summary": "Added reusable claims, explicit source locators, and matching Markdown and JSON. This publishing change does not itself establish factual verification." }, { "date": "2026-10-02", "kind": "content-revision", "summary": "Added “Separate the 2017 fork rules from present-day product claims”, clarified the search description. Independent verification is recorded separately." } ], "citation": "Degrees of Satoshi editorial project. “Bitcoin Cash: why Bitcoin split on 1 August 2017, and what happened to both sides after.” Published 2026-09-23; updated 2026-10-02. https://degreesofsatoshi.com/encyclopedia/bitcoin-cash-fork-2017/" }