The Ethereum community continues to make important strides ahead of the planned advent of “Ethereum 2.0” next year.

The latest of these strides was unveiled on September 9th, when the builders behind the Lighthouse and Nimbus ETH 2.0 clients — the Sigma Prime and Status teams respectively — announced their clients had achieved what appeared to be the “first instance of finality on a multi-client Eth2 testnet,” Sigma Prime’s Paul Hanner noted.

Let’s break the milestone down a bit. In the context on Ethereum, a client is a piece of software that allows a user to verify and interface with the blockchain. Beyond Lighthouse and Nimbus, there are several ETH 2.0 clients in the works, including Prysm, Parity, Harmony, and Hyperledger Besu.

🙌 #ETH2 is coming! 🙌 If you needed a reason to celebrate today here is one: the first instance of finality on a multi-client #ethereum 2.0 testnet! 🥳🍾🥂 ✨#EpicAchievementUnlocked✨ Big kudos everyone!!! 👏👏👏 https://t.co/qOsfuE9xFn — Mihai Alisie (@MihaiAlisie) September 9, 2019

With that said, the recent interaction between the Lighthouse and Nimbus looks like the first time that two separate clients have finalized an ETH 2.0 testnet epoch together. Here, finality refers to the concept of transactions becoming irreversible, and epoch refers to a group of 100 blocks in the upgraded Ethereum blockchain.

In other words, some of the important early work that will help actualize Ethereum’s coming evolution is coming along as needed in the here and now.

That evolution, which will take place across the multi-phase Serenity upgrade, is set to begin at some point next year. Ethereum Foundation researcher Justin Drake has previously suggested that early 2020 could be the launch point for Phase 0 of Serenity, though that suggestion may end up being optimistic.

Whenever Phase 0 starts, it will mark the formal beginning of Ethereum becoming a new blockchain altogether — one that willy rely on proof-of-stake consensus, sharding, and Plasma tech.

“Ethereum 2.0 is going from this experimental project that Vitalik launched just a few years ago to a more production ready blockchain protocol,” Peter Mauric, Parity’s Head of Public Affairs, told CoinDesk last year.

Istanbul Hard Fork Has Important Test Scheduled for Next Month

Istanbul will be the last major network upgrade that Ethereum will undergo before the platform’s roadmap shifts to Serenity next year.

Notably, an Istanbul testnet was set to launch on September 4th, but Ethereum’s core developers decided last week to postpone that testnet to October 2nd in order to have more time to review more Ethereum Improvement Proposals (EIPs) for inclusion in Istanbul.

The postponement means that Istanbul’s scheduled activation on the mainnet will also be pushed back, now being set for some time during November.

“Let’s start with setting the testnet fork and see how that goes and find a period of stability before revisiting when to set the mainnet fork,” E.G. Galano, lead infrastructure engineer for Infura, said during a developer call on September 6th.

Whenever it does go live, the upgrade will enact a series of optimizations. Namely, Istanbul will allow storage costs to be lowered, zk-SNARKs to be used cheaper, and some opcode prices to be changed. Moreover, Istanbul will allow interoperability between Ethereum and Zcash by making it so Ethereum smart contracts can verify Equihash PoW.

More Coming Out of Ethereum Interop Lock-In

Over the weekend, teams working on clients across the Ethereum 2.0 ecosystem came together for a “lock-in,” wherein those involved hunkered down for a few days to experiment as alpha testers for each other’s software.

This is ETH2.0 history in the making. See the full list of goals that the ETH2.0 teams are trying to accomplish during the #Interop Lock-in: https://t.co/Dw6E9BSROp https://t.co/W5a7Uy3xQy — DeFi Pulse 🍇 (@defipulse) September 8, 2019

Set to take place for a few more days, the lock-in should produce more milestones and help in smoothing the path to ETH 2.0. For one, the Artemis and Lighthouse clients have also begun interacting.

“It is incredibly important for clients to document their progress, any issues that arise during this process (non-comforming components, coordination issues, debugging nightmares, etc), and the solutions that they employ to address these issues,” the event’s GitHub page reads.