Ethereum’s Pectra upgrade hit an unexpected roadblock Monday when it failed to finalize on the Holesky testnet, revealing potential issues that could delay the blockchain’s most significant update in nearly a year.
The test was activated Monday afternoon at 4:55 ET but failed to achieve finality, according to data from Beacon Chain, an open-source blockchain explorer. The transactions are potentially irreversible—a critical flaw for a network built on immutability.
The Ethereum Foundation, a non-profit dedicated to supporting the development and growth of the Ethereum ecosystem, did not immediately respond to a request for comment.
In Ethereum, finality ensures transactions become irreversible after approximately 13 minutes (equal to two “epochs”). Transactions become “final” when at least two out of three validators agree they’re confirmed, making reversals nearly impossible.
To reverse a finalized transaction, attackers would need to control at least a third of all staked ETH—but the smart contract would automatically burn their stake if they tried, making it too risky to attempt.
“Holesky and other testnets exist to find issues,” Georgios Konstantopoulos, general partner and chief technology officer at crypto investment firm Paradigm, said on X.
Konstantopoulos noted that the bug was isolated to execution clients that had issues where “they forgot to add the correct deposit contract address.”
The issue was centered on “how deposit contract addresses were handled by these clients,” Joshua Cheong, product lead at Ethereum Layer-2 protocol Mantle Network, told Decrypt.
The non-finality issue “resulted in network instability,” representatives from Mantle Network said.
This happened because the Pectra upgrade introduced new Ethereum system contracts and moved deposit tracking from the Consensus Layer to the Execution Layer.
Some EL clients had configuration errors tracking deposits, disrupting critical hash verifications that were needed for withdrawals and deposits, Mantle Network explained.
Pectra represents a package of 11 crucial protocol improvements, headlined by EIP-7702, a wallet enhancement proposal drafted by Ethereum co-founder Vitalik Buterin.
That effectively allows wallets to temporarily act as smart contracts during transactions, enabling features like batch operations and gas fee sponsorships without permanent changes to accounts.
The technical hiccup comes amid growing pressure on Ethereum to accelerate its development cycle, all while Ethereum core developers disagree on what features to load up for Pectra.
Last month, Paradigm said that Ethereum’s core protocol could be improving much faster.
“Historically, Ethereum has shipped about one change per year. Ethereum can do more,” Konstantopoulos wrote alongside other Paradigm researchers.
This tension between careful testing and faster shipping surfaces as the stakes for Ethereum continue rising.
Institutional players particularly await EIP-7251, which would increase validator staking limits from 32 to 2,048 ETH, potentially transforming how its economy moves.
Edited by Sebastian Sinclair
Editor’s note: This story was updated to add response from Mantle Network.
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