Ethereum announced the successful completion of its Constantinople/St. Petersburg upgrade on February 28, 2019. Previous network upgrades have been given other names such as Spurious Dragon and Byzantium.
If you are an Ethereum user or hold ether and use an exchange (such as Coinbase, Kraken, or Binance), a web wallet service (such as Metamask, MyCrypto, or MyEtherWallet), a mobile wallet service (such as Coinbase Wallet, Status.im, or Trust Wallet), or a hardware wallet (such as Ledger, Trezor, or KeepKey) no immediate action is required.
Node operators or miners should download and install the latest version of the client software that will automatically update at the same block number associated with this latest release.
Because blockchain systems are decentralized, network upgrades are more difficult. A successful network upgrade in a blockchain requires various levels of cooperation and communication with the Ethereum community, as well as with the developers of the various Ethereum clients in order for the transition to go smoothly and avoid the risks associated with a hard fork.
A hard fork occurs when a single cryptocurrency splits in two. When a cryptocurrency’s existing code is changed, resulting in an old and new version where the two versions are incompatible, we experience the problem of the hard fork. For example, if someone is using an Ethereum client that is not updated to the latest version as part of the Constantinople/St. Petersburg upgrade, your client will sync to the pre-network upgrade blockchain once the upgrade occurs. This means that you will be stuck on an incompatible chain following the old rules and you will be unable to send ether or operate on the post-upgrade Ethereum network.
Ethereum has issued a community notice and been in regular contact with its users and broader community throughout the planned upgrade to avoid any unnecessary issues.
As of this morning (March 1, 2019) Ethereum is currently trading at $134.98.