Sepolia Merge Announcement

Introduction

The Sepolia testnet is set to undergo its transition from Proof-of-Work (PoW) to Proof-of-Stake (PoS), marking the second of three public testnets scheduled for the Merge. This critical upgrade will occur when Sepolia's PoW chain reaches a Terminal Total Difficulty (TTD) of 17,000,000,000,000,000, expected within the coming days.

Post-Merge, Sepolia will feature a permissioned validator set, similar to existing PoA testnets. In contrast, the Goerli/Prater testnet—slated for Merge later—will open its validator set, allowing stakers to test the PoW-to-PoS transition.

Background

After years of development to bring PoS to Ethereum, the ecosystem has entered its final testing phase: testnet deployments.

Following Ropsten’s successful transition to PoS and ongoing shadow forks, Sepolia is now Merge-ready. Once Sepolia completes its Merge, only the Goerli/Prater testnet remains before mainnet preparations begin. Other testnets (Ropsten, Rinkeby, and Kiln) will gradually deprecate post-Merge. For details, refer to the Testnet Deprecation Announcement.

The Merge differs from prior Ethereum upgrades in two key ways:

1. Node operators must update both their Consensus Layer (CL) and Execution Layer (EL) clients.

2. The upgrade activates in two phases:

   • Bellatrix (a beacon chain epoch height)
   • Paris (triggered by TTD on the execution layer).

Sepolia’s Bellatrix upgrade is already live. We now confirm Phase 2 details: the TTD threshold.

Upgrade Specifications

Timeline

The Merge occurs in two steps:

1. Bellatrix: Activated at epoch 100 on June 20, 2022, preparing the Sepolia Beacon Chain.
2. Paris: Triggered when Sepolia’s PoW chain hits a TTD of 17,000,000,000,000,000, expected imminently.

Once TTD is reached:

• The next block will be produced entirely by Beacon Chain validators.
• Finalization occurs ~13 minutes after the first post-TTD block.

Infrastructure providers should monitor:

• The new finalized JSON-RPC tag.
• The PREVRANDAO opcode (formerly DIFFICULTY) to confirm Merge completion.

Client Releases

Consensus Layer Clients

• Lighthouse: v2.3.2-rc.0
• Lodestar: v0.39.0-rc.2
• Prysm: v2.1.3-rc.4
• Nimbus: v22.6.1
• Teku: v22.6.1

Execution Layer Clients

• Besu: v22.4.3 (Requires manual TTD override)
• Erigon: v2022.06.06 (Manual TTD override)
• Geth: v1.10.20
• Nethermind: v1.13.4

FAQ

For Node Operators

• Post-Merge, run both CL and EL clients.
• Configure JWT authentication for secure client communication.
• Monitor APIs: Beacon Chain and JSON-RPC remain operational.

👉 Learn how to configure JWT for secure communication

For Stakers

• Sepolia’s validator set is permissioned; no action required unless already a validator.
• For Goerli/Prater, prepare to run an EL client post-Merge and set a fee recipient address.

For Developers

• Test on Ropsten/Kiln before Sepolia. Report issues via merge-testnets.
• Migrate from deprecated testnets (Ropsten/Rinkeby/Kiln) to Sepolia/Goerli.

For ETH Holders

• No action needed. Mainnet is unaffected.

For Miners

• Mining will cease post-Merge on Sepolia (and later mainnet).

👉 Explore post-Merge Ethereum staking opportunities

Additional Notes

• Validators cannot withdraw staked ETH yet. Withdrawals are planned for a post-Merge upgrade.
• Community Q&A scheduled for July 15 UTC. Details to follow.

Disclosure: Mainnet Merge date remains unconfirmed. Follow official channels for updates.

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