The Merge changed how Ethereum agrees

Inherited archive entry · retained from the earlier edition. Its factual, legal and policy claims have not all been reverified for 19 September 2026. Research scope.

A change of engine

Ethereum's Merge occurred on 15 September 2022, according to Ethereum's current technical overview. The existing mainnet execution layer joined the Beacon Chain's proof-of-stake consensus layer. Transactions and application state continued on Ethereum; the method used to propose and agree on new blocks changed. That is more precise than saying that all of Ethereum was replaced by a new chain.

What had to happen

The August 2022 mainnet announcement described two linked steps: a Beacon Chain upgrade called Bellatrix, followed by the execution layer transition at a specified total difficulty. The trigger was not simply a calendar alarm. Node operators needed compatible execution and consensus clients. Once the transition occurred, proof-of-work mining ceased to be Ethereum mainnet's consensus method and validators took over block production under proof of stake.

This changed security assumptions. Instead of miners expending work and receiving block rewards for finding blocks, validators stake ether and face protocol penalties for certain violations. The question for readers is not whether one mechanism is automatically safer. It is which resources an attacker must control, what participants can observe, and how the network responds to misbehavior or correlated failure. Those questions require evidence beyond an energy comparison.

What it did not promise

The overview says historical data and users' existing funds carried through; users did not need to move funds to a supposed 'new ETH'. It also explains that the Merge itself did not make transactions cheaper or increase throughput. A marketing claim that a later fee change was delivered by the Merge should therefore identify the separate upgrade or layer responsible. Similarly, a change in ether issuance is a protocol fact, not a price forecast. Ethereum's issuance explainer treats issuance and fee burning as separate flows whose net result depends on activity.

The scheduled announcement and the later documentation serve different roles. The former establishes what operators were told before the event; the latter establishes the observed date and present technical description. Keeping those dates separate avoids making a pre-event estimate appear to be the final event record.

Questions after a major upgrade

• Which layer changed: execution, consensus, or an application?
• Which safety assumption changed, and which risks stayed with the user or service?
• Is a claimed benefit part of this upgrade or a different roadmap item?

The lesson is institutional as well as technical. A chain can coordinate a profound change and preserve its application history, but the act of coordination does not certify every application or predict the value of its asset.