What is a Hard Fork?

A hard fork related to blockchain technology improvements. It is a radical change to a network’s protocol that makes previously invalid blocks and transactions valid or vice versa.

When a hard fork happens, it requires all its computers and users to upgrade to the latest version of the protocol software.

Who decides on hard forks?

Hard forks occur because they are deemed to be necessary in a network’s protocol in order to better its version and necessary upgrades. It is initiated by its developers or members of the cryptocurrency community. When the crypto community is not satisfied with the crypto’s functionalities they will seek to improve it.

Hard forks are very important upgrades to a cryptocurrency since they can attract new investors to the scene. It is also a sort of proof that the developers are willing to take the crypto one step further.

How do users upgrade to the new version?

A hard fork is when nodes of the newest version do not accept the older version of the blockchain. Adding the new rules to the code creates a fork in the blockchain that goes like this:

The old path follows the new path (which is the upgraded blockchain) and the other path continue on the old one. Nodes on the old version will realize that they need to upgrade to the newest version sooner or later since the blockchain will become irrelevant.

Latest Hard Fork


The latest hard fork that we have experienced was the Ethereum Berlin-Hard Fork that went live on April 15th at block number 12,244,000.

The Berlin hard fork was a network upgrade that incorporated four Ethereum improvement proposals (EIP) that tinker gas prices and allow new transaction types. The upgrade was just a stepping stone on the Ethereum blockchain since the London hard fork will activate next the EIP 1559, a momentous (and controversial) change to Ethereum’s fee structure.

The Berlin Hard Fork EIPs are:

  • EIP-2929, increases gas costs for “op code” transactions, a pain point for denial of service attacks on Ethereum in the past.
  • EIP-2930, a new transaction type (made possible by EIP-2718’s envelope transactions) which allows its users to create templates for future, complex transactions in a bid to lower gas costs.
  • EIP-2565, which reduces gas cost for a specific transaction type that uses modular exponentiation.
  • EIP-2718, makes all transaction types “backwards compatible” using so-called “envelope transactions,” which allows the addition of new transaction logic into Ethereum.

Read the full article “From Berlin To London, To Ethereum’s 2.0 Bullish Year”.

How do Forks work?


Forks can occur in any cryptocurrency just like it occurred in Ethereum. This is because blockchains and cryptos in general work in the same way. Each block in the blockchain carriers all the memory (previous transactions and history that happened in each block) and since miners set the rules that more the memory, they are the ones who understand the new rules better than anyone.

However, all the miners in different geographic locations need to agree on the new rules so when you want to change those rules you basically need to fork it to indicate that there’s been a change in or a diversion to the protocol.


Investopedia says “It is through this forking process that various digital currencies with names similar to bitcoin have come to be, bitcoin cash, bitcoin gold, and others.

Why do Hard Forks happen?


Just like the Berlin hard fork happened to better how transactions and gas fees are being processed there can also be various reasons why developers may implement a hard fork. Another example is when Ethereum blockchain created a hard fork to reverse the hack on the Decentralized Autonomous Organization (DAO).

When the hack happened, the community voted in favor of a hard fork to roll back transactions that siphoned off tens of millions of dollars wort of digital currency by an anonymous hacker. The DAO helped the Ethereum holders get their funds back.

Just to clear things up, the new hard fork did not erase or unwind the network’s transaction history but instead it just relocated the funds tied to the DAO to a newly created smart contract with a single purpose of letting the original owner withdraw their funds. How amazing is that?

Read more about blockchains to understand how they work and function.