Ethereum Mainnet Merge Official Announcement

Introduction

Ethereum is transitioning to Proof-of-Stake (PoS) through a historic upgrade known as The Merge. This process begins with the Bellatrix upgrade on the Beacon Chain, followed by the migration of Ethereum's Proof-of-Work (PoW) chain to PoS upon reaching a specific Total Terminal Difficulty (TTD) value.

Key Milestones:

Bellatrix Upgrade: Activated at Beacon Chain epoch 144896 on September 6, 2022, 11:34:47 UTC.
Paris Upgrade: Triggers at TTD 58750000000000000000000, expected between September 10–20, 2022.
Testnet Closure: Kiln testnet will shut down on September 6, 2022.

Background

After years of development, Ethereum’s PoS upgrade is finally here! All public testnets have successfully upgraded, and the mainnet merge is scheduled. The Merge differs from previous network upgrades in two ways:

Node operators must update both Consensus Layer (CL) and Execution Layer (EL) clients.
The upgrade occurs in two phases: Bellatrix (consensus layer) and Paris (execution layer).

Upgrade Details

Timeline

Phase	Trigger Condition	Estimated Date
Bellatrix	Beacon Chain epoch 144896	September 6, 2022
Paris	TTD ≥ 58750000000000000000000	September 10–20, 2022

👉 Track real-time merge progress

Once TTD is reached:

Beacon Chain validators produce subsequent blocks.
Merge completion is confirmed after ~13 minutes (2 epochs).
A new finalized JSON-RPC tag will indicate merge completion.

Client Requirements

Node operators must run both EL and CL clients. Below are supported versions:

Consensus Layer Clients

Lighthouse, Lodestar, Nimbus, Prysm, Teku

Execution Layer Clients

Besu, Erigon, go-ethereum, Nethermind

Critical Warning: Avoid geth v1.10.22 due to database issues—upgrade to v1.10.23 immediately.

Merge Specifications

Consensus Changes: Defined in the Bellatrix directory.
Execution Changes: Outlined in the Paris specification.
Client Interaction: Governed by the Engine API and Optimistic Sync.

Merge Bug Bounty

From now until September 8, 2022, merge-related bug rewards are 4x higher, with critical issues eligible for up to $1 million. Details available here.

FAQs

1. What should node operators do?

Merge requires running both EL and CL clients.
Configure JWT authentication for secure communication.
Refer to Running a Node for setup steps.

2. What changes for stakers?

Validators must pair their CL client with an EL client.
Set a fee recipient address to receive transaction fees.
Use the Merge Checklist for preparation.

3. Why is the TTD date range wide?

TTD depends on fluctuating PoW hash rate. More hash rate = faster TTD achievement.

4. How should developers prepare?

Test contracts on Sepolia or Goerli.
Verify frontend tools and APIs (avoid PoW-specific methods like eth_getWork).

5. Do ETH holders need to act?

No action required for users holding ETH in wallets or exchanges. Beware of scams!

👉 Secure your ETH post-merge

6. Can PoW miners continue?

No. Post-merge, Ethereum operates solely on PoS. PoW mining becomes obsolete.

7. What if I don’t upgrade my node?

Non-upgraded clients will sync to the pre-fork chain, becoming incompatible with the PoS network.

8. When can stakers withdraw ETH?

Withdrawals are not enabled in The Merge. Expect this feature in a future upgrade.

9. Where to ask more questions?

Join the Merge Community Call on September 9, 14:00 UTC, with core developers and researchers.

Acknowledgments

A monumental thank you to all contributors—researchers, developers, testers, and advocates—who made The Merge possible. The Ethereum community’s collective effort has built this groundbreaking upgrade.

Final Note: The Merge is coming—very soon.


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