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 major aim of the testnet is to practice Ethereum’s mainnet merge by the year-end. The Ethereum core developers have conducted 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. This is the same process that the Ethereum mainnet merge will go through later.
The Ropsten merge is one of the series of 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, and go-Ethereum (get), and Nethermind. The coming merge will only occur after the proof-of-work version of the Ropsten crossed a pre-decided metric called terminal total difficulty. This is set to a very high level of 50 quadrillions to prevent any malicious entity from messing with the merge by artificially acquiring the hash rate (which happened the first time this test was scheduled).
Since Ropten is a testnet,hashrates is low. However, the merge node operators will have to manually configure their clients to bypass the Ropten Terminal total difficulty(TTD), both for their execution layer and consensus player 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 tenets, including Goerli and Sepolia.