Jul 262 mins read

Ethereum's Constantinople Hard Fork Delayed Until End of February

Security vulnerability discovered prior to scheduled launch

Ethereum's Constantinople Hard Fork Delayed Until End of February

Ethereum core developer Peter Szilagyi has announced that the Ethereum core development team has decided to delay the Constantinople hard fork until the end of February. The delay is due to a security vulnerability that was discovered prior to the scheduled launch on January 15th. The hard fork will now occur at block height 7,280,000, which is expected to be on February 27th.

What is the Constantinople hard fork?

The Constantinople hard fork is a planned upgrade to the Ethereum network’s underlying technology. This upgrade is expected to implement a single fork on the main network and fix the Constantinople fork on the test network to keep them consistent with the main network's functionality.

Security Vulnerability Related to EIP-1283

The vulnerability was related to EIP-1283, which aimed to make SSTORE operations cheaper on gas costs. If launched, it could have made some existing smart contracts more susceptible to reentrancy attacks, allowing attackers to steal cryptocurrency from the contracts and falsify their Ethereum account balance data.

Delays and Issues

The delay has caused some issues for Ethereum, particularly with miners who have not yet installed the latest Ethereum software on non-official chains. Furthermore, there remains a question of how to implement lower transaction fees and other improvements in the upgrade.

Constantinople Hard Fork Updates

The Constantinople hard fork includes five EIP updates, including a delay to the difficulty bomb and block reward adjustment, an introduction to the EXTCODEHASH opcode, and the ability to create new types of smart contracts.

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The Constantinople Hard Fork


The Constantinople hard fork is a transitional period for Ethereum to move towards a more efficient Proof-of-Stake (PoS) consensus algorithm from the current Proof-of-Work (PoW) algorithm.


The upgrade is necessary due to the "Difficulty Bomb" issue, which will affect block times on the Ethereum network. The delay of 6 weeks is considered fair and reasonable, and developers need to remove the code related to EIP-1283 as part of the final upgrade.


Additionally, they must ensure the safe operation of Ethereum client wallets. The CREATE2 opcode for state channels is discussed along with introductions to gas calculation and bitwise shift operations in EIP-1283 and EIP-145, respectively.