List of bitcoin forks
Bitcoin forks are defined variantly as changes in the protocol of the bitcoin network or as the situations that occur "when two or more blocks have the same block height". A fork influences the validity of the rules. Forks are typically conducted in order to add new features to a blockchain, to reverse the effects of hacking or catastrophic bugs. Forks require consensus to be resolved or else a permanent split emerges.
Forks of the client software
All three software clients attempt to increase transaction capacity of the network. None achieved a majority of the hash power.
Intended hard forks splitting the cryptocurrency
Hard forks splitting bitcoin (aka "split coins") are created via changes of the blockchain rules and sharing a transaction history with bitcoin up to a certain time and date. The first hard fork splitting bitcoin happened on 1 August 2017, resulting in the creation of Bitcoin Cash.
The following is a list of hard forks splitting bitcoin by date and/or block:
- Bitcoin Cash: Forked at block 478558, 1 August 2017, for each bitcoin (BTC), an owner got 1 Bitcoin Cash (BCH)
- Bitcoin Gold: Forked at block 491407, 24 October 2017, for each BTC, an owner got 1 Bitcoin Gold (BTG)
- Bitcoin SV: Forked at block 556766, 15 November 2018, for each Bitcoin Cash (BCH), an owner got 1 Bitcoin SV (BSV).
Intended soft forks splitting from not-most-work block
- The fork fixing the value overflow incident was controversial because it was announced after the exploit was mined. It was assigned CVE-2010-5139.
Unintended hard forks
Two hard forks were created by "protocol change" definition:
- March 2013 Chain Fork (migration from BerkeleyDB to LevelDB caused a chain split)
- CVE-2018-17144 (Bitcoin 0.15 allowed double spending certain inputs in the same block. Not exploited)
Intended hard forks (no split)
- BIP 90 is claimed by libbitcoin contributor Eric Voskuil to be a hard fork.
- BIPs 68, 112, 113 (CSV), 141, 143, and 147 (segwit) buried in 2019 likewise claimed to be a hard fork by Voskuil.
- Antonopoulos, Andreas (2017). Mastering Bitcoin: Programming the Open Blockchain (2 ed.). USA: O' Reilly media, inc. p. Glossary. ISBN 978-1491954386.
- Ammous, Saifedean (2018). The Bitcoin Standard: The Decentralized Alternative to Central Banking. John Wiley & Sons. pp. 227, 228. ISBN 9781119473893. Retrieved 23 April 2018.
- March 2013 Chain Fork
- BIP number designations: https://github.com/bitcoin/bitcoin/pull/16060/files#r299495299
- Hard fork designation: https://lists.linuxfoundation.org/pipermail/bitcoin-dev/2019-August/017268.html
- Merged pull request: https://github.com/bitcoin/bitcoin/pull/16060