SegWit2xB2X (planned)
The planned 2 MB hard fork that was meant to follow SegWit under the New York Agreement, suspended a week before its block height.
The wiki's angle: SegWit2x is the half of a deal that never shipped. The SegWit half activated in August 2017; the 2 MB half was suspended, which Bitcoin Takeover's fork table treats as the end of hard-fork attempts on the main chain.[8][3]
Contents
The plan
The SegWit2x project announced that about 90 days after SegWit activated, miners would produce a block between 1 MB and 2 MB, and it expected more than 90% of hashpower to keep mining on top of it[1]. Most clients would only need to change two constants: maximum block weight from 4,000,000 to 8,000,000 and sigops per block from 80,000 to 160,000[1].
Where it came from
The announcement says the 2 MB upgrade was first agreed at the Bitcoin Roundtable in Hong Kong in February 2016 and ratified by the New York Agreement in May 2017[1]. The New York text committed signers to activate SegWit at an 80% threshold signalling on bit 4, and to activate a 2 MB hard fork within six months[2].
Suspension
On 8 November 2017 Mike Belshe posted that “it is clear that we have not built sufficient consensus for a clean blocksize upgrade at this time” and that the group was “suspending our plans for the upcoming 2MB upgrade”[3]. The message was signed by Belshe, Wences Casares, Jihan Wu, Jeff Garzik, Peter Smith and Erik Voorhees[3].
Aftermath on the podcast
On S16 E60, Jonathan Bier recalled that after the cancellation email the Bitcoin Cash price briefly reached about 51% of Bitcoin's, a moment he attributes largely to retail speculation on Korean exchanges[4]. On S17 E19, Amaury Séchet said Roger Ver joined Bitcoin Cash only after SegWit2x failed, “two months later … something like that”, a recollection this wiki has not checked against the record[5].
Heard on Bitcoin Takeover
BTCPay Server creator Nicolas Dorier said on S15 E14 (December 2023): “I was definitely against SegWit2x. It's basically what made me start BTCPay Server”.[6]
In the same episode he summarised the 2017 split: “Most developers were for just SegWit. Most big companies were for SegWit2x, most miners were for SegWit2x.”[7]
References
- primarysegwit2x.github.io, “Bitcoin Upgrade at Block 494,784” [archived]
- primaryDigital Currency Group, “Bitcoin Scaling Agreement at Consensus 2017”, Medium, 23 May 2017 (Wayback Machine copy)
- primaryMike Belshe et al., “Segwit2x Final Steps”, bitcoin-segwit2x mailing list, 8 Nov 2017 (Wayback Machine copy)
- episodeS16 E60: Jonathan Bier — the SegWit2x cancellation and the BCH price spike▶ listen at 2:01:14timestamp transcript-derived, pending a listen [archived]
- episodeS17 E19: Amaury Séchet — Roger Ver joined BCH after SegWit2x failed▶ listen at 3:48:59timestamp transcript-derived, pending a listen [archived]
- episodeS15 E14: Nicolas Dorier on opposing SegWit2x▶ listen at 25:42timestamp transcript-derived, pending a listen [archived]
- episodeS15 E14: Nicolas Dorier on who backed SegWit2x▶ listen at 29:12timestamp transcript-derived, pending a listen [archived]
- btkBitcoin: All the Hard Forks and Soft Forks (BTCTKVR: Forks!) [archived]