Challenges Faced by Ethereum’s Pectra Upgrade
Ethereum’s highly anticipated Pectra upgrade encountered an unexpected hurdle on Feb. 24 during its testing phase on the Holesky testnet.
Root Cause of the Failure
Tim Beiko, Ethereum Foundation Protocol Support Lead, revealed on Feb. 27 that the issue stemmed from execution clients—Geth, Nethermind, and Besu—utilizing incorrect deposit contract addresses.
- Execution clients using wrong deposit contract addresses
- Triggered an execution layer (EL) bug causing chain splits
This misconfiguration led to a chain split, leaving a minority chain functional and compromising the network’s overall health.
Impact on Ethereum’s Upgrade Process
The incident has sparked concerns about the resilience of Ethereum’s upgrade process, especially since Pectra is set to bring significant changes to the blockchain network. This upgrade is considered Ethereum’s most ambitious hard fork, divided into two phases aimed at improving developer and user experiences.
Response and Next Steps
Ethereum core developers have already taken action to address the issue, scheduling a mass validator slashing event on Feb. 28 at 15:00 UTC.
- Updating and syncing nodes
- Disabling slashing protection before slot 3,737,760
The objective is to bring sufficient Holesky validators online simultaneously to finalize a block on the correct chain. Validators supporting the invalid chain will face slashing, enabling consensus layer (CL) clients to sync with the valid network.
Continued Challenges and Recovery
Despite mitigation efforts, Holesky will undergo a period of non-finality for up to three weeks. Slashed validators will exit during this time, reducing their stake below the requisite 33%. Once this threshold is met, remaining validators can properly finalize the chain.
Developers are exploring ways to streamline the process of redirecting nodes to a minority chain more efficiently in future scenarios.
Timeline for Pectra Upgrade
It remains uncertain whether the setback with Holesky will impact the timeline for the Pectra upgrade. Developers are evaluating the testing that was planned on Holesky and considering the best approach before scheduling a mainnet fork date.
Despite the uncertainty, developers are committed to launching Pectra’s next testnet upgrade on Sepolia on March 5. Unlike Holesky or mainnet, Sepolia operates with a permissioned validator set controlled by client and testing teams, facilitating quicker coordination and reducing the risk of disruptions.
Enhanced Testing Window
Expediting the fork on Sepolia will provide developers with an extended testing period for Pectra, enhancing the upgrade’s overall readiness.
