Lead developer, Péter Szilágyi, announced the new schedule for Ethereum Constantinople will be on 27 February. The team is aiming for block 7,280,000 for the fork
A vulnerability, spotted by ChainSecurity AG, was the cause for the delay. The upgrade will be delivered in two successions. The first will carry five of the intended Ethereum Improvement Proposals (EIPs). EIP 1283, where the vulnerability was found, will not be included in the second upgrade. Szilágyi remarks that a single fork will happen on the mainnet with a ‘post-Constantinople-fixup fork’ on testnets done to fit its features with the main network.
Seems we're going with block 7.28M for the #Ethereum Constantinople refork scheduled for the 27th of February! Will be a single fork on mainnet and a post-Constantinople-fixup fork on the testnets to get them back in line feature wise with the main network.— Péter Szilágyi (@peter_szilagyi) January 18, 2019
This two-part idea by Szilágyi attempts to assure the easy implementation of the fix for testnets and private networks that implements the upgrade. Nodes are required to upgrade the whole system since the fork will radically change the Ethereum blockchain; backward compatibility will be inhibited.
First delayed in November last year, Ethereum Constantinople is an upgrade meant to switch consensus from proof-of-work to proof-of-stake. It will also reduce a miner’s block rewards and delay the difficulty bomb for a 12-month period.
Exchanges such as Binance, Coinbase, Huobi, and OKEx confirmed support for Constantinople.