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A change to a blockchain’s rules that older software does not accept, so every node must upgrade or the chain can split in two.
Crypto Drafted with AI help · Reviewed by Keshav Aggarwal · Updated
In simple words
Imagine a board game where everyone agrees to a new rule, like “you may now move two squares”. Players who keep the old rulebook can no longer play at the same table.
A hard fork is that kind of rule change for a blockchain: everyone who wants to keep playing together has to update.
The technical side
A hard fork changes a blockchain’s consensus rules so that blocks valid under the new rules are rejected by nodes running the old software. If part of the network does not upgrade, the chain can split in two. A soft fork, by contrast, only tightens the rules, so old nodes still accept the new blocks.
On 4 November 2026, Binance and Polymarket filed a Polygon governance proposal for a hard fork that would move about 70.49 million POL (about $6.8m), taken in two hacks, from five attacker addresses to recovery wallets at a set block. Bitcoin developers, meanwhile, discuss the Great Consensus Cleanup (BIP-54) as a possible next soft fork. More on our Crypto hacks tracker.
Hard Fork kya hai?
Blockchain ke rules mein bada badlav, jise purana software nahi maanta. Sabko upgrade karna padta hai, warna chain do hisson mein bant sakti hai.
Not investment advice. Crypto tokens can lose all their value. Read the risk disclaimer.
Related terms
- BlockchainCryptoA shared record of transactions, copied across many computers, where each new block of entries is linked to the one before it.
- Proof of StakeCryptoA way for a blockchain to agree on new blocks where validators lock up coins as a deposit instead of using mining power.
- Smart ContractCryptoA program stored on a blockchain that runs by itself when its conditions are met, such as releasing funds once a payment arrives.
- Layer 2CryptoA network built on top of a main blockchain, such as Ethereum, that handles transactions faster and cheaper and then reports back to it.