ACDC #161: Call Minutes

The call where developers discussed the free option problem in ePBS

Jul 25, 2025

Good evening,

Ethereum developers have narrowed down a short list of consensus layer candidates for the Glamsterdam headliner, and they plan to reach a final decision on it in two weeks.

They also discussed a significant risk associated with one of the shortlisted candidates that could lead to a higher rate of empty blocks on Ethereum.

Below is my full call summary for All Core Developers Consensus Call (ACDC) #161.

Yours truly,

Christine D. Kim

🛎️ Programming note: As a heads-up, the ACD After Hours newsletter will be going on a two-week break from Monday, July 28, to Friday, August 8. I’ll be soaking up some sun over on the West Coast and attending Paradigm’s Frontiers conference in San Francisco. Coverage of the ACD calls will resume Monday, August 11!

Key Decisions & Announcements

(For background on the ACD process and jargon used on these calls, refer to the Ethereum Governance 101 document in the ACD Toolkit.)

Fusaka

Nethermind and Lodestar nodes are having syncing issues on Fusaka Devnet-2.
The Fusaka upgrade has been scheduled to activate on Fusaka Devnet-3 later today.
Many clients are having issues with their implementation of EIP 7910 (eth_config JSON-RPC Method) on Fusaka Devnet-3.
There are also issues in the MEV workflow that developers are trying to resolve so that they can test updated MEV software, such as builders, relays, and MEV-Boost, on Fusaka Devnet-3.
Ethereum Foundation (EF) Protocol Team Co-Lead and Chair of the ACDC Calls, Alex Stokes, reiterated the timeline for shipping Fusaka on Ethereum mainnet is as follows:
- Fusaka Release Candidate (RC) client versions ready by September 1
- First public testnet upgrade by September 15 or 22
- Second public testnet upgrade by October 6
- Ethereum mainnet upgrade by November 5

Glamsterdam

Ethereum Foundation Researcher Maria Silva gave a presentation on the viability of six-second slot times.
Flashbots Researcher Christoph Schlegel gave a presentation on the free option problem of slot restructuring.
Lighthouse developer “Dapplion” shared concerns about shipping enshrined proposer builder separation (ePBS) in Glamsterdam.
Stokes said that the following three consensus layer (CL) focused Ethereum Improvement Proposals (EIPs) will be considered for inclusion (CFI’d) in Glamsterdam.
- EIP 7732, ePBS
- EIP 7783, six-second slot times
- EIP 7805, fork choice enforced inclusion lists (FOCIL)
Stoked added that over the next two weeks, more feedback on these three EIPs will be gathered from the Ethereum community, and developers will aim to make a final decision on the next ACDC call.

Nimbus developer Etan Kissling requested a review of a new pull request (PR) to CL specifications based on his headliner proposal for Glamsterdam, Pureth.

Notable Discussion

(Quotes featured in this section may be edited slightly for grammar and clarity. For more information on the people quoted in this section, refer to the ACD Call Directory in the ACD Toolkit.)

The free option problem

After Silva's presentation, Schlegel explained a major risk introduced by ePBS and other proposals like it that restructure the components of block validation.

Schlegel explained that due to the extended window of time that block builders have to propose their blocks in ePBS, builders have a higher likelihood of cancelling their blocks at the last second.

Builders can cancel their blocks by withholding blob transactions from a block.

Thus, the more lucrative the payoff for preventing the execution of certain transactions in a block and reordering them in another block, the more likely it is that empty blocks will be proposed on Ethereum.

Schlegel said:

“The entire [ePBS] design is meant as a pipelining, some sort of architecture where we postpone blobs to the end of the slot. That gives you a bunch of time to actually wait for this last deadline, for the blobs, wait whether something happens that is informative to you, and usually this is about trading financial information. Then you could choose not to send the blob. It's about eight seconds. If you want to take away one thing from this presentation, it’s that eight seconds is a lot, and that gives you possibly a lot of value to this option.”

Schlegel stressed that this is a problem with any proposal that separates execution payload validation from consensus block validation and extends the period of execution payload validation.

His colleague at Flashbots Bruno Mazorra explained that the most effective solution to addressing the free option problem is to shorten the period for execution payload validation.

However, this reduces the benefits of ePBS and slot restructuring, as the extended period for payload validation is what frees up bandwidth and resource consumption in validator nodes during block proposals.

Other potential solutions included additional slashing or penalties on builders that cancel their blocks, blacklisting builders that engage in last-minute cancellations for financial gain, and separating blob from transaction inclusion in a block.

One of the main authors of ePBS, Prysm developer “Potuz,” wrote in the Zoom chat:

“I don’t see any solution really. It’s fundamental to have the blob deadline late.”

EF Researcher Francesco D'Amato echoed:

“How can we [schedule for inclusion in Glamsterdam] something where we have such a big unresolved question?”

Community feedback

After the presentations by Silva and Schlegel, developers discussed what the headliner or main feature should be for the Glamsterdam upgrade on the CL.

Nixo Rokish, who is part of the EF’s Protocol & Application Support Team, highlighted feedback from Ethereum stakeholders like Lido, Flashbots, Snowbridge, and more on this Ethereum Magicians thread.

Based on his view of developer sentiment, Stokes suggested tentatively approving ePBS for Glamsterdam and reconfirming this decision on the next ACDC call.

EF Developer Operations Engineer Barnabas Busa asked:

“What do we wanna do about FOCIL for Glamsterdam?”

EF Protocol Architecture Co-Team Lead Dankrad Feist said that in his view, community support for six-second slot times is higher than ePBS.

EF Researcher Thomas Thiery said in his view, the community ranks FOCIL as a “top tier” choice for Glamsterdam.

Stokes and EF Protocol Coordination Co-Team Lead Tim Beiko both expressed concerns about bundling ePBS and FOCIL in the same upgrade.

Busa asked:

“Wasn’t one of the pre-requisites of having something [considered for inclusion in a fork] to have at least one working prototype implementation?”

About the proposal for six-second slot times, Potuz shared concerns about its lack of specification:

“I think the major blocker for that [one] is the fact that it's not even specified. We are going to need to touch issuance, and [we haven’t] even looked into how hard that part would even be. We need to touch at least the base reward … and it's not really clear how invasive that change would be.”

Stokes suggested creating a short list of CL candidates for Glamsterdam and restricting the list to the following three proposals:

EIP 7732, ePBS
EIP 7805, FOCIL
EIP 7783, six-second slot times

Rokish highlighted that the Ethereum community should make their voices heard on the Glamsterdam fork by contributing to this Ethereum Magicians thread.

🌻That’s all for my summary on ACDC #161. You are officially caught up on the state of Ethereum protocol development and governance. Stay tuned for my insights on the call coming out tomorrow.

🌻New to the ACD calls and want to learn how to engage in them yourself? Check out the ACD Toolkit. It contains evergreen resources and materials that teach you the fundamentals of contributing to the evolution of Ethereum like a pro:

ACD Toolkit

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Book a meeting

Below are links for further reading and watching on the topics discussed on ACDC #161:

An MEV Perspective on Glamsterdam (Flashbots)
Glamsterdam Community Call #00 Recap and Follow-ups (Christine D. Kim)
The case for block-level access lists in Glamsterdam (Toni Wahrstätter)
MEV-Boost Community Call #13 Video Recording (PBS Foundation)

Here’s what’s coming up next week on the Ethereum Protocol Call Calendar:

Monday July 28

14:00 UTC/10:00 ET, All Core Developers Testing Call #46 (Meeting link shared on Discord)
15:00 UTC/11:00 ET, Stateless Implementors Call #39

Tuesday July 29

14:00 UTC/10:00 ET, FOCIL Implementors #16 (Meeting Zoom link)
16:00 UTC/12:00 ET, EIP Editing Office Hour Meeting 67 (Meeting link shared on Discord)

Wednesday July 30 (Ethereum’s 10th anniversary!)

14:00 UTC/10:00 ET, Post Quantum Interop Breakout (Meeting Zoom link.)
- New meeting series! Information about it has been added to the ACD Toolkit.

Thursday July 31

14:00 UTC/10:00 ET, All Core Developers Execution Call #217 (Meeting link shared on Discord)

Friday August 1

No calls scheduled on this day.

📅 Call days and times may be subject to change so please utilize the links shared above to reconfirm meeting details day of. For a comprehensive overview of all recurring calls and meetings on the Ethereum Protocol Call calendar, refer to this post in the ACD Toolkit.📅

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