Announcement of Sepol Merger | Ethereum Foundation blog

  • Sepolia will be the second of three public test networks to tour The Merge.
  • The network will transition to a demonstration of interest when the overall difficulty on the proof chain is overcome. 17,000,000,000,000,000which is expected to happen around in the next few days.
  • Upon merger, Sepolia will have a permit validator, such as existing evidence from authoritative test sites. Goerli / Prater, which will merge at a later date, will keep an open validator to allow participants to test the transition.


After years of working to bring proof of interest to Ethereum, we are now well into the final test stage: testnet deployments!

With Ropsten already transitioned to proof-of-interest and shadow forks continuing on a regular basis, Sepolia is now ready for The Merger. After Sepolia, only Goerli / Prater will have to be merged before moving to mainland. Other test sites will be considered deprecated after merging, as explained in a recent post.

The Merger differs from previous Ethereum updates in two ways. First, node operators must upgrade both their consent layer (CL) and execution layer (EL) clients in tandem, rather than just one of the two. Second, the update activates in two phases: the first at epoch height on the Beacon Chain and the second hitting Total Difficulty value on the execution layer.

Sepolia has already run through the Bellatrix update on the Beacon Chain. We are now announcing the details of the second phase of the transition: hitting the Terminal Total Difficulty.

Update Information


The Merger is a two-step process. It starts with a network update on the consent layer, triggered by an epoch height. This is followed by the transition from the execution layer of proof of work to proof of interest, triggered by a specific Total Difficulty threshold, called the Terminal Total Difficulty (TTD).

On June 20, 2022is epoch 100the Belatrix an update prepared the Sepulcher Beacon Chain for The Merger. At that point, CL customers started listening for a TTD value hit on the proof-of-work chain.

Because the hash percentage of proof-of-work test networks is highly volatile, the TTD value was first set to an extremely high value, 100000000000000000000000. At the current hash rate of Sepolia, it would take hundreds of years to reach this value.

With Bellatrix now live, updated TTD value of 17000000000000000 was chosen for the transition. It is expected to be hit within the next few days. When this new TTD is hit or exceeded, the execution layer part of the transition, coded Paris, will begin. Again, note that hash rate on Sepolia is notoriously variable, so the actual time when the Terminal Total Difficulty happens can vary.

After the execution layer has exceeded the TTD, the next block will only be produced by Beacon Chain validator. We consider that The Merger ended after the Beacon Chain finished this block. Assuming normal network conditions, this should happen 2 epochs, or about 13 minutes, after the first post-TTD block is hit!

New JSON-RPC block tag, finalized, returns the last completed block or error if such a post-merge block does not exist. This tag can be used for applications to check if The Merger has been completed. Similarly, smart contracts can the question DIFFICULTY opcode (0x44)renamed to PREVRANDAO post-merger, to determine whether The Merger took place. We recommend that infrastructure providers monitor overall network stability in addition to ultimate status.

Customer Editions

The following customer releases support The Merge on the Sepolia test network. Node operators must work both execution and consent layer client to remain on the network during and after The Merger.

When choosing which client to run, validators should pay particular attention to the risks of managing a majority client on both the EL and CL. An explanation of these risks and their consequences can be found here. An estimate of current EL and CL customer distribution and guidelines for switching from one customer to another can be found here.

Agreement Table

Execution Layer

Name Version Link
Besu See “Kiss Note” below See “Kiss Note” below
Erigon See “Erection Note” below See “Erigon note” below
go-ethereum (geth) v1.10.20 Download
Nethermind 1.13.4 Download

Besu Note: to be compatible with the Sepolia merger, Besu users will have to perform a manual Terminal Total Difficulty to rule. To do this, users must run the latest edition of Besu, 22.4.3 since the publication of this post, and do the following:

  • If you are using TOML configuration files, add the following line: override-genesis-config=["terminalTotalDifficulty=17000000000000000"]
  • If you start the node with the CLI, add the following flag: --override-genesis-config="terminalTotalDifficulty=17000000000000000"

Erigon Note: to be compatible with the Sepolia merger, Erigon users will have to perform a manual Terminal Total Difficulty to rule. To do this, users should run the 2022.06.06-alpha release and add the next flag when the node is started --override.terminaltotaldifficulty=17000000000000000 should be good for Sepolia.

More information on TTD dominance can be found in the Ropsten TTD Announcement.

Upgrade Specifications

Agreement-critical changes for The Merge are specified in two areas:

  • The consent layer changes, below the bellatrix directory of the deposit of consent types
  • The execution layer changes, below the Paris spec in the repository of execution specifications

In addition to these, two other specifications cover how the consent and execution layer clients interact:

  • The Engine API, specified in the execution-apis depotis used for communication between the consent and execution layers
  • Optimistic Sync, specified in the sync a directory of the consent type repository, is used by the consent layer to import blocks while the execution layer client is synchronizing and to provide a partial view of the head of the chain from the first to the last.

Frequently Asked Questions

As a node operator, what should I do?

Post-merger, an Ethereum-full node will combine a consent layer client that runs the proof-of-stake Beacon Chain, and an execution layer client that manages the user state and runs the computations associated with transactions. These communicate via an authenticated port using a new set of JSON RPC methods called the Engine API. The EL and CL client authenticate each other using a JWT secret. Node operators should refer to their customers ’documentation for instructions on how to generate and configure these.

In other words, if you’ve already run a node on the Beacon Chain, you now also need to run an execution client. Similarly, if you were to run a node in the current proof network, you would have to run a consent layer client. In order for them to communicate securely, a JWT token must be delivered to each customer.

It is worth emphasizing that while they are both part of consent layers client editions, running a Beacon Node is different from running a Validator Client. Stakers have to run both, but node operators only need the first one. This post explains the difference between the two components in more detail.

Also, note that each layer will maintain an independent set of peers and display its own APIs. La Signpostango and JSON RPC APIs both will continue to work as expected.

As a staker, what should I do?

The Sepolia validator is allowed, so unless you have already been included as a Sepolia validator, no action is required.

The transition from Goerli / Prater to a demonstration of interest, which will be announced at a later date, will be open to all validators. Below are some notes to prepare for that. Again, no action is required now.

As explained above, validators on the Beacon Chain will have to run an execution layer client after The Merge, in addition to their consent layer clients. Prior to merging, this was strongly recommended, but validators could have outsourced these features to third-party providers. This was possible because the only data required on the execution layer were updates to the deposit contract.

After merging, validators must ensure that transactions in blocks that they create and certify are valid. To do this, each beacon node must be paired with an execution layer client. Note that multiple validators can still be paired to a single beacon node & runtime client combo. While this expands the responsibilities of validators, it also gives a validator that offers a blockchain the right to its related transaction priority fees (which currently go to miners).

While validators rewards are obtained on the Beacon Chain and will require a subsequent online update to be withdrawn, transaction fees will continue to be paid, burned and distributed on the execution layer. Validators can specify any Ethereum address as a recipient for transaction fees.

After updating your consent client, be sure to customize the fee recipient as part of your validator client settings to ensure transaction fees are sent to an address you check.

If you packaged using a third-party provider, it is up to your chosen provider to specify how these fees are allocated.

If you would like to test the operation of a validator on post-merger Ethereum, instructions are available at Ropsten staking launch pad.

As an application or tool developer, what should I do?

With The Merge running on Sepolia, now is the time to make sure your product works as expected through the demonstration of interest transition and in a post-merger context. As explained in a previous post, The Merger will have only a minimal impact on a subset of contracts deployed on Ethereum, none of which should be broken. Additionally, most user API endpoints remain stable (unless you use demonstration-specific methods such as eth_getWork).

That said, most applications on Ethereum involve much more than chain contracts. Now is the time to ensure that your front code, gear, deployment manifold, and other out-of-chain components are working as intended. We strongly recommend that developers go through a complete test and deployment cycle on Ropsten (or Kiln) and report any problems with tools or dependencies to the maintainers of those projects. If you are not sure where to open a problem, please use this deposit.

Additionally, it should be noted that all test sites except Sepolia and Goerli will be deprecated after merging. If you are a user of Ropsten, Rinkeby or Kiln, you should plan to migrate to Goerli or Sepolia. More information on this can be found here.

As an Ethereum user or Ether owner, is there anything I need to do?

No. The main theme of Ethereum is not affected by this text. Subsequent announcements will be made on this blog prior to the mainstream transition.

As a miner, is there anything I need to do?

No. If you are mining on the main network of Ethereum or Sepolia, you should be aware that each network will work completely under proof after The Merger. At that point, mining will no longer be possible on the net.

This is expected in the coming days on Sepolia and later this year for the main network of Ethereum.

As a validator, can I withdraw my interest?

No. The Merger is the most complicated upgrade to Ethereum to date. To minimize risks of network interruptions, a minimum approach was taken that excluded any non-transition changes from this update.

Withdrawals from the Beacon Chain are likely to be introduced in the first update after The Merger. Specifications for both the consent and execution layers are in progress.

I have additional questions, where can I ask them?

A Merge Community Call is scheduled for July 15, 14:00 UTC. Client developers and researchers will be available to answer questions from node operators, stakers, infrastructure and tool providers and community members.

to merge

Since the publication of this post, the date for the Ethereum main transition of proof of interest has no was fixed. Any source who claims otherwise will likely be a fraud. Updates will be posted on this blog. Please stay safe!

Assuming no problems are found with Sepolia, once customer testing is complete, Ethereum’s other EL test network, Goerli, will go through The Merge with the Prater CL testnet. After Goerli / Prater has successfully crossed and stabilized, an era will be chosen for the Bellatrix upgrade on the main Beacon Chain and difficulty value will be configured for the mainframe transition. Customers will then make releases that enable The Merge on mainstream. These will be announced on this blog and in other community publications.

This assumes that no problems are found. However, if problems are found at any point in the process or test coverage is deemed insufficient, these issues will be addressed before proceeding with the deployment process.

Only then will it be possible to estimate the exact date for The Merge.

In other words,.



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