What is a hard fork?

August 23, 2018 | Updated April 23, 2026

Medium min reading

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Essential Points

Breakdown of Consensus: This is a mandatory update and is incompatible with previous versions. If you don't update your node or wallet software, you will be removed from the main network.
Divergence of Paths: By changing the code rules, the chain splits in two. Both share the past history, but write a completely different future with their own tokens.
Motivations: They are run to patch critical security bugs or to resolve ideological disputes about how the protocol should scale.
The real example: The split between Bitcoin and Bitcoin Cash. While the former prioritizes security with small blocks, the latter sought speed by increasing block size. Currently, this mechanism is the ultimate governance tool in the cryptocurrency ecosystem.

A hard fork isn't just a simple software update you download to your phone and forget about. It's a drastic change to the rules of the game. When the nodes of a network decide to modify the protocol in such a way that the new version becomes incompatible with the previous one, the blockchain is irreversibly split in two.

If you don't update your client, you'll be left behind. It's that simple. Unlike the soft forksWhere the system maintains some backward compatibility, here we're talking about a complete breakdown of consensus. What does this mean for us? Basically, that we must choose sides if we want our digital assets to continue operating on a valid network.

Why force a break in the network?

Sometimes, the code fails. In those cases, a hard fork acts like emergency surgery to correct errors that jeopardize the integrity of cryptocurrencies. Other times, the reason is purely ideological or technical: one part of the community proposes an improvement that the other half completely rejects.

Imagine you're hiking with your friends in the mountains. As long as you're all walking along the same trail, you share the same view and the same destination. But suddenly, you reach a fork in the path. If the group splits up, each side will have a different experience from that point on, even though both perfectly remember the route taken up to the turn. The same thing happens with blockchain technology: the past transaction history is inherited, but future paths are completely independent.

The Bitcoin Cash Case: A Divorce Foretold

The clearest example of this phenomenon can be found in the Bitcoin network. For years, the community debated how to scale the network to process more transactions per second. Faced with this lack of agreement, Bitcoin Cash was born, a token that decided to take its own path by prioritizing block capacity.

BitcoinIt maintains 1MB blocks, prioritizing security and extreme decentralization, which limits its processing capacity to a few transactions per second.
Bitcoin CashThey opted to increase the block size to 32MB. This achieves greater speed, yes, but at the cost of further centralizing the node infrastructure.

Is a fast network better than an ultra-secure one? There's no single answer. What is undeniable is that, after a hard fork, the market and users dictate which proposal survives the test of time. Currently, we see how these forks define project governance, forcing us to pay close attention to every repository update if we don't want our tokens to end up on a ghost chain.

FAQ – What is a Hard Fork?

What happens to my digital assets if a hard fork occurs?

If you hold your tokens in a hardware wallet or under your own custody before the fork, you'll automatically have a balance on both chains. It's like a technical "two for one." However, if you leave your funds on an exchange, you'll be entirely dependent on whether the platform decides to support the new network or not. That's why, in this world, we often say that if you don't have the keys, you don't really have control.

Is a hard fork the same as a routine update?

No. A regular update is usually a minor patch that doesn't break compatibility. A hard fork is a structural change to the validation rules. Imagine a game's instruction manual changing mid-game: if you don't accept the new rules, you simply can't continue playing at the same table as everyone else.

Why do some hard forks create a new token and others don't?

It all depends on consensus. If the entire community agrees that the change is necessary (for example, to fix a critical bug), everyone migrates to the new version, and the old chain dies from neglect. The new cryptocurrency only emerges when there is a division of opinion and some miners and users decide to keep the previous version of the code alive.

Are these processes dangerous for network security?

The main risk is a denial-of-service attack, or user confusion. During the first few hours of a fork, the network can be unstable. Additionally, there's a risk that someone might try to trick you into sending your tokens to one chain and inadvertently losing them to the other. Developers typically implement safeguards against this, but caution is always best.

Who has the power to decide when a hard fork is made?

There's no boss or board of directors. The real power lies with the nodes that validate transactions and the miners who secure the network. If developers propose a change the community doesn't like, the nodes simply won't install the software. At the end of the day, it's a system of technical democracy where code only matters if people choose to run it on their computers.

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Author

Javier Pastor

Director of Institutional Training and Communication

Javier Pastor is specialized in Marketing and has training at the Chinese School of Business and International Business. He has experience as a sales specialist and international sales specialist in numerous companies.