• Ethereum is moving to proof-of-stake! The transition, known as The Merge, must first be activated on the Beacon Chain with the Bellatrix upgrade. After this, the proof-of-work chain will migrate to proof-of-stake upon hitting a specific Total Difficulty value.
• The Bellatrix upgrade is scheduled for epoch 144896 on the Beacon Chain – 11:34:47am UTC on Sept 6, 2022.
• The Terminal Total Difficulty value triggering The Merge is 58750000000000000000000, expected between Sept 10-20, 2022.
• Note: as announced earlier, the Kiln testnet is being sunset. Operators will shut down on September 6, 2022.

Background

Following years of hard work, Ethereum’s proof-of-stake upgrade is finally here! The successful upgrade of all public testnets is now complete, and The Merge has been scheduled for the Ethereum mainnet.

The Merge is different from previous network upgrades in two ways. First, node operators need to update both their consensus layer (CL) and execution layer (EL) clients in tandem, rather than just one of the two. Second, the upgrade activates in two phases: the first, named Bellatrix, at an epoch height on the Beacon Chain, and the second, named Paris, upon hitting a Total Difficulty value on the execution layer.

Upgrade Information

Timing

The Merge is a two-step process. The first step is a network upgrade, Bellatrix, on the consensus layer triggered by an epoch height. This is followed by the execution layer’s transition from proof-of-work to proof-of-stake, Paris, triggered by a specific Total Difficulty threshold called the Terminal Total Difficulty (TTD).

The Bellatrix upgrade is scheduled for epoch 144896 on the Beacon Chain – 11:34:47am UTC on Sept 6, 2022.

Paris, the execution layer’s portion of the transition, will be triggered by the Terminal Total Difficulty (TTD) of 58750000000000000000000, expected between Sept 10-20, 2022. The exact date at which TTD is reached depends proof-of-work hash rate. Estimates for the transition can be found at bordel.wtf and 797.io/themerge.

Once the execution layer reaches or exceeds the TTD, the subsequent block will be produced by a Beacon Chain validator. The Merge transition is considered complete once the Beacon Chain finalizes this block. Under normal network conditions, this will happen 2 epochs (or ~13 minutes) after the first post-TTD block is produced!

A new JSON-RPC block tag, finalized, returns the latest finalized block or an error if no such post-merge block exists. This tag can be used by applications to check if The Merge has been completed. Similarly, smart contracts can query the DIFFICULTY opcode (0x44) (renamed to PREVRANDAO post-merge) to determine if The Merge has happened. We recommend infrastructure providers monitor overall network stability in addition to finalization status.