The Ethereum (ETH) network will be undergoing a planned hard fork at block number 4.37 Million (4,370,000), which will likely occur between 12:00 UTC and 13:00 UTC on Monday, October 16, 2017. Ethereum users should update to the latest version of the Ethereum wallet/Mist if they are using it as well as any of the Ethereum clients – Geth, Parity or Harmony prior to the hard fork in order to be ready. Ethereum websites and mobile applications that allow you to store ether and/or make transactions are running their own Ethereum client infrastructure to facilitate their services and they should be doing the update as well in order to support he hard fork as well.
A hard fork is a change to the underlying Ethereum protocol, creating new rules to improve the system. The protocol changes are activated at a specific block number. All Ethereum clients need to upgrade, otherwise they will be stuck on an incompatible chain following the old rules. Metropolis is a planned Ethereum development phase that includes two hard forks: Byzantium and Constantinople. Byzantium is occurring at block number 4.37M (the hard fork happening tomorrow), while the second part – Constantinople does not currently have a release date, but is expected to happen some time in 2018.
– Here is a countdown for the time remaining until the Byzantium Hard Fork of Ethereum…