Ethereum’s Dencun Upgrade Live on Testnet After Bug Delays Finalization – Unchained

The Ethereum Dencun upgrade launched on the testnet but failed to finalize for four hours due to a bug that has since been patched.

Ethereum core developers confirmed that the Dencun upgrade went live on the Goerli testnet on Wednesday, after a few hiccups that prevented the network from finalizing within the expected time. 

The goerli fork finalized! 😀https://t.co/LIa3d4Ml5H

After the fix was patched in, the validators came back online and the chain started finalizing again. The MEV circuitbreaker automatically disables and mev-blocks have started flowing through as well.

Yay client diversity! https://t.co/cLz3ZRxnXq

— parithosh | 🐼👉👈🐼 (@parithosh_j) January 17, 2024

The fork was implemented at around 6 am UTC, after which developers noticed a low validator participation rate of around 80%. For context, the chain will typically lose finality if approximately 10% of validators are offline. 

Tim Beiko, the Ethereum core developer that runs the core developer meetings, noted that there had been a chain split due to the lack of finalization and client teams were looking into the issue.

“Prysm encountered a bug right at Goerli’s hard fork. The bug has been identified, and a fix is currently being merged. A hot patch image will be released within the next few hours,” said Ethereum developer terence.eth in a post on X shortly after.

Around four hours later, Ethereum developer Parithosh Jayanthi, confirmed that the Goerli fork had finalized after the fix was patched in and validators came back online. Jayanthi said that a more detailed analysis of the incident would be discussed during the All Core Developer meeting on Thursday. 

Tune in to ACD tomorrow for a full incident report. But I do want to mention that we went from fork -> issue -> triage -> fix -> finality in under 4h. The debugging apparatus has gotten great!

— parithosh | 🐼👉👈🐼 (@parithosh_j) January 17, 2024

The highly anticipated Dencun upgrade introduces EIP-4844 on the network, implementing the protodanksharding mechanism that brings blob carrying transactions onto the blockchain. 

These transactions will lower transaction costs for Ethereum Layer 2 networks by “sharding” data storage instead of splitting the blockchain into smaller bits when storing temporary off-chain data.

The upgrade is expected to be deployed on the mainnet at the end of the first quarter in 2024, after its activation on the Sepolia testnet and the Holesky testnet.