Segwit2x logo

SegWit2x was a proposed hard fork of the cryptocurrency Bitcoin. The fork was slated to occur on 16th November 2017, but was cancelled due to lack of consensus. The fork would have increased the block size to 2 megabytes. Segregated Witness has been previously activated on the Bitcoin chain from which SegWit2x would have forked[1].


What is segwit2x?

SegWit2x Definition – SegWit 2x is a new policy proposal for the cryptocurrency bitcoin that is now under consideration in the bitcoin community. It builds on a prior protocol called Segregated Witness or SegWit

  • The tentative date of fork: 28.12.2017
  • Total issuance: 21 million coins
  • Protection against re-transaction: yes
  • Rate of production: 2.5 min block
  • Mining protocol: X11
  • Block size: 4 MB
  • Difficulty recalculation: after each block
  • Official website:


Bitcoin Hardfork Segwit2x – HOW TO DOUBLE YOUR BITCOIN!

A picky look at the B2X (SegWit2x) project shows that it is not trying to update the Bitcoin Protocol, but creates another Altcoin that will trade the bitcoin brand.

For starters, the development team of this project is quite different than the one that worked on the initial proposal, which was led by Bitcoin Core developer Jeff Garzik.

In addition, the fact that developers embody protection against rewriting and a unique address structure is a tacit admission that B2X is not bitcoin – a significant diversion against the position expressed by the defenders of the original offer [[SegWit2x].

Network B2X will also be pre-main. According to the website of the project, the developers will take over the distribution of funds belonging to wallets created by the founder of bitcoin Satoshi Nakamoto (Satoshi Nakamoto). The developers claim that these funds will be divided among those “who support the network”, but there are very few details regarding this process.

It is worth noting that the SegWit2x Protocol has completely different characteristics than bitcoin, which was also to inherit a new coin, as it were not called bitcoin or not, in the case of the original hard fork Segwit2x. The network will be protected using the X11 encryption algorithm rather than SHA-256, and it will have a 2.5-minute block extraction interval rather than a 10-minute one as the original network. The complexity will be listed after each block, and as advertised by the site, zkSNARK technology will be implemented in order to allow users to make anonymous transactions. Perhaps the most ironic of all is that developers increase the block size to 4 MB, instead of 2 MB, which is mentioned in the name of hard fork.

Given these factors, as well as the haste with which developers have initiated a new hard fork, the community has reason enough to accept this project with skepticism, and users should be careful to protect their bitcoins in the BTC blockchain by transferring them to a new wallet address before they attempt to interact with the B2X network[2].

In a comment for the CCN, the developers wrote, ” We took that name to recover everything that was behind SegWit2X. Our fork is not an alternative, it is the same fork that failed in November, but now it is with improved functionality, we were not going to force anyone.”

In addition, in the roadmap of the project is planned following positive changes:

  • Offline codes
  • Lightning Network support, instant transactions
  • ZkSnarks Technology
  • Smart contract support
  • Anonymous transactions


The implementation of Segregated Witness in August 2017 was the first half of the so-called “New York Agreement” in which those who wanted to increase effective block size by SegWit compromised with those who wanted to increase block size by a hard fork to a larger block size. The second half of SegWit 2X involves a hard fork in November 2017 to increase the blocksize to 2 megabytes. Some companies that originally supported the New York Agreement backed-out, including F2Pool, Bitwala and Wayniloans[3].


A major issue of contention was the choice by the SegWit2x developer not to implement mandatory replay protection. Opt-in replay protection means that the Segwit2x chain will still accept transactions intended for the original chain, in addition to replay-protected transactions only valid on Segwit2x. Users sending transactions on the Bitcoin chain, or who failed to send replay-protected Segwit2x transactions, would have been vulnerable to having their transactions replayed to the other chain, resulting in accidental loss of funds. This absence of strong replay protection has created considerable controversy in the bitcoin community.


On November 8, 2017 the developers of SegWit2x announced that the planned hard fork had been canceled, due to a lack of sufficient consensus.

Network Failure

Although the stated reason for the cancellation of the hardfork was “lack of consensus”, several bugs in the codebase would have prevented the fork from occuring. The official fork was planned to occur at block height 494,784, however the actual code stalled waiting for block height 494,783 due to an off-by-one coding error.

The hash rate of miners signaling in favor of Segwit 2x subsequently dropped to below 10% and all nodes running the B2X (SegWit2x) software have permanently stalled on block 494,782.

Security with Segwit2X during the hard fork implementation

It is recommended to refrain from conducting transactions, as this may not be safe. If the miners deliberately to break the rules of consensus, users can lose your coins. If the controversial hard fork fails, it will be safe to continue using mobile wallets — follow the news and take action in time. At the end of the hard fork block generation may slow down, which will affect the speed of transactions at a higher level of processing commissions. In this case, if there are important transactions, it is recommended to spend a few days before the hard fork.

External links

See Also on BitcoinWiki


  1. Analysis: the New SegWit2x has Nothing to Do with the Cancelled
  2. Jeff Garzik Is Reworking the Segwit2x Code – CoinDesk
  3. Hard Fork, Take Two: SegWit2x Will Return Dec. 28, Says Founder – CoinTelegraph