Ethereum's Ropsten test merge expected to initiate in next 48 hours

Quick Take

Ethereum’s core developers have imminent plans to perform “the merge” on the Ropsten testnet.
This event will merge Ropsten’s proof-of-work chain with its beacon chain

Ropsten, Ethereum's oldest testnet, is about to undergo its transition to proof of stake — as one of the final tests ahead of the merge on the main Ethereum blockchain. While the exact timing for the Ropsten merge will fluctuate depending on a few variables, it's expected to happen on Wednesday, according to an official blog post from Ethereum.

The main objective of the testnet merge is to practice Ethereum's mainnet merge later this year. The Ethereum core developers have carried out merge tests in the past, including a shadow fork on the main network and another merge on a testnet called Kiln.

This event will take Ropsten’s two chains — one proof of work, the other being the proof-of-stake beacon chain — and combine their code together. This is the same process that the Ethereum mainnet merge will go through later.

The Ropsten merge is one of the many critical steps to check whether client software used to run Ethereum nodes performs normally and without bugs during the event. Several client software teams participating in the coming Ropsten merge include Lighthouse, Lodestar, Prysm, Nimbus, Teku, Besu, Erigon, go-ethereum (geth) and Nethermind.

The coming merge will only happen after the proof-of-work version of Ropsten crosses a pre-decided metric called terminal total difficulty. This is set to a very high level of 50 quadrillion as to prevent any malicious entity from messing with the merge by artificially acquiring hashrate (which happened the first time this test was scheduled).

Since Ropsten is a testnet, its hashrate is low. Therefore, the merge node operators will have to manually configure their clients to override the Ropsten Terminal Total Difficulty (TTD), both for their execution layer and consensus layer clients. This is scheduled to be completed by the end of today.

As soon as clients report and fix issues observed in the Ropsten merge, the developers will move to other merge tests planned on other testnets, including Goerli and Sepolia.