Ethereum Foundation offers details on Istanbul Hard Fork upgrade

The Community Leader of the Ethereum Foundation, Hudson Jameson, has confirmed that the Instanbul Hard Fork will be releasing on December 7, 2019. The exact time frames are subject to change because of variable block times. The Ethereum node operators should upgrade their nodes before December 1, 2019, to account for the variable block times. Users can track the upgrade's progress online using Ethernodes tools, giving a real-time status of preparations made by miners, exchanges, developers and nodes. 

Additionally, the official announcement had a list of final releases that are compatible with the Istanbul upgrade. In addition to Geth and Parity, some exotic implementations include Aleth, Besu and Nethermind. The announcement also included a warning. Once the update occurs, if a user uses an Ethereum client that is not up-to-date, then the node client will sync back to the pre-fork blockchain. This blockchain will not be compatible with the new Ethereum and will not be able to send ether or operate on the post-upgraded Ethereum network.

The Ethereum Foundation said that if users are holding Ethereum (ETH) and/or utilize web wallets, mobile apps, exchanges, and hardware wallets, then they should not upgrade their tools unless asked by administrators of these services. The Istanbul Hard Fork is the last of Ethereum 1.0, as this will open a direct road to the next status of settlement in the Ethereum network - Serenity.