# Hard Fork No. 4: Spurious Dragon

DevFeed: [Hard Fork No. 4: Spurious Dragon](<https://devfeed.tech/articles/hard-fork-no-4-spurious-dragon-16789.md>)

Original publisher: [Read original article](<https://blog.ethereum.org/en/2016/11/18/hard-fork-no-4-spurious-dragon>)

Author: Hudson Jameson

Published: 2016-11-18T18:19:46Z

Content type: release

Language: en

Sources: [Ethereum Foundation Blog](<https://devfeed.tech/sources/ethereum-foundation-blog.md>)

Topics: [Ethereum](<https://devfeed.tech/topics/ethereum.md>), [Network](<https://devfeed.tech/topics/network.md>), [Blockchain](<https://devfeed.tech/topics/blockchain.md>), [Protocol (disambiguation)](<https://devfeed.tech/topics/protocol.md>)

Tags: [attacks](<https://devfeed.tech/tags/attacks.md>), [blockchain](<https://devfeed.tech/tags/blockchain.md>), [ethereum](<https://devfeed.tech/tags/ethereum.md>), [fork](<https://devfeed.tech/tags/fork.md>), [network](<https://devfeed.tech/tags/network.md>), [protection](<https://devfeed.tech/tags/protection.md>), [protocol](<https://devfeed.tech/tags/protocol.md>), [protocol-announcements](<https://devfeed.tech/tags/protocol-announcements.md>), [transactions](<https://devfeed.tech/tags/transactions.md>)

## AI overview

Ethereum announced the Spurious Dragon hard fork, planned for block 2,675,000 on November 22, 2016. The upgrade included replay-attack protection, opcode pricing changes, and blockchain-state debloating, and required clients to update for compatibility.

## Source excerpt

The Ethereum network will be undergoing a hard fork at block number 2,675,000, which will likely occur between 15:00 and 16:00 UTC on Tuesday, November 22, 2016. A countdown timer can be seen at https://fork.codetract.io/. The Morden test network will be undergoing a hard fork at block number 1,885,000....