Bitcoin XT – The Forgotten First Bitcoin Hard Fork

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  • Bitcoin XT was a planned hard fork, pushed in 2014 by Mike Hearn and Gavin Andresen
  • The hard fork launched in August 2015 with an 8mb block size
  • After finding initial success, Bitcoin XT lost user interest and was abandoned

When Bitcoin split into Bitcoin and Bitcoin Cash in 2017, the cryptocurrency world was on the edge of its seat wondering what would happen. Would Bitcoin Cash take over? Would Bitcoin die? Would they both survive and forge their own paths? It was this unknown that was the cause of such comment and consternation. However, many didn’t realize that Bitcoin had already experienced a hard fork two and a half years previously, one pushed by Bitcoin luminaries Mike Hearn and Gavin Andresen no less, called Bitcoin XT, which you will no longer find on the cryptocurrency charts. What was Bitcoin XT, what did it stand for, and what happened to it? Let’s find out.

Bitcoin’s Block Size Problem

The genesis of Bitcoin XT was dissatisfaction from a number of Bitcoin developers, including big hitters Hearn and Andresen, over the looming capacity crisis on the Bitcoin network. By 2015, each Bitcoin block was reaching its 1mb capacity, which Hearn, Andresen and others warned would result in a bottleneck of transactions.

To remedy this, Hearn called for an increase to 8mb blocks, alongside other less significant changes, which he formalized in Bitcoin Improvement Protocol 101 (BIP 101). BIP 101 was torpedoed however by what Hearn referred to in an August 2015 blog post as “a small group of people” who “fear success” and wanted to keep things as Satoshi Nakamoto had stated in the Bitcoin whitepaper – a 1mb block.

This group, the core of developers who wielded great control over the Bitcoin protocol, preferred to focus instead on other scaling solutions such as the Lightning Network, which, at this point, was just a theoretical rather than a practical solution.

Hearn Throws Down the Gauntlet

Hearn’s response was to implement his desired changes into Bitcoin XT, which he had already soft-launched in 2014 as a way of introducing alternative P2P rules. This implementation of BIP 101 into the Bitcoin XT protocol was a gauntlet thrown down to the community, with Hearn explaining in a developer messagebaord post on launch day that “the Bitcoin Core project has drifted so far from the principles myself and many others
feel are important, that a fork is the only way to fix things.”

The Bitcoin XT hard launch gained media attention and brought the scaling debate out into the open. Hearn argued that the 1mb block size was never meant to be permanent and was implemented in order to keep the blockchain manageable in Bitcoin’s early days, but that the handbrake could now be released given Bitcoin’s size. However, he accused the developer core of intentionally holding back from this in order to push other ideals.

DDOS Attacks and Dirty Tricks?

Whatever the merits of it, it would be the nodes and miners who would decide whether Bitcoin XT lived or died. Bitcoin XT initially saw success, with more than 1,000 nodes running its software in the late summer of 2015, but this success didn’t last – miners failed to support the project and towards the end of 2015 it lost user interest and was essentially abandoned by node operators and miners.

Hearn claimed that Bitcoin XT “pushed powerful emotional buttons in a small number of people” and that discussion of it and its principles was all but outlawed on the Bitcoin forums he and his co-developers used. He also posted reports of DDOS attacks on Bitcoin XT node operators and datancenters supporting them, claiming that “around a third of the nodes were attacked and removed from the internet in this way.”

Hearn alleges other dirty tricks levied against Bitcoin XT users and node operators, with miners allegedly terrified of rocking the boat and supporting the project. Whatever the truth of these allegations, Bitcoin XT eventually fell away and the project’s website went offline, leaving Hearn and Andresen to lick their wounds, and Hearn to watch on as Bitcoin’s price soared to $20,000 in the 18 months after he sold up.

“Bitcoin Has Failed”

Hearn voiced his anger at the failure of Bitcoin XT and the actions of the Bitcoin Core community in January 2016, penning a blog post entitled “The resolution of the Bitcoin experiment”. In it he voiced his opinion that the Bitcoin he knew was dead:

But despite knowing that Bitcoin could fail all along, the now inescapable conclusion that it has failed still saddens me greatly. The fundamentals are broken and whatever happens to the price in the short term, the long term trend should probably be downwards. I will no longer be taking part in Bitcoin development and have sold all my coins.

Hearn added that “the network is on the brink of technical collapse” following the rejection of the block size increase, with Hearn’s comments being seized on by the mainstream media, who gleefully (and mistakenly) reveled in Bitcoin’s apparent death.

Hearn has, of course, proved to be right in that Bitcoin’s blockchain is full. Bitcoin blocks hit the 1mb barrier in March 2017 and only increased in size when Segwit allowed expansion to 1.5mb. What he appears to have been wrong about however is the Lightning Network, which continues to take more and more pressure off the blockchain.

Bitcoin XT Philosophy Lives On

In the immediate aftermath of the Bitcoin XT experiment, another fork, Bitcoin Classic, emerged with a 2mb block size. This saw even more support than Bitcoin XT initially, but soon went the same way as its cousin. It still exists, but barely.

Hearn may not have achieved his goal of a cap-less Bitcoin, but his efforts did lead indirectly to the Bitcoin Cash fork in 2017, which has the same 8mb block size, and Bitcoin SV, which has removed the block size cap altogether and should perhaps be renamed Bitcoin MHV.

Very few people who joined the Bitcoin space during the 2017 bull run or later will have heard of Bitcoin XT, and while this first Bitcoin fork may have led nowhere in itself, its legacy still remains in other Bitcoin forks that are still fighting to get the same message out.