Ethereum’s forthcoming Dencun upgrade is now live on the Georli testnet, but its deployment did not initially go as planned.

The Goerli Dencun fork took place on Jan. 17 at around 1:35 am, replacing the gas-intensive calldata with blobs through EIP-4844. The upgrade, also referred to as proto-danksharding, will increase data availability and significantly reduce transaction fees on Layer 2, in addition to laying the infrastructure for Ethereum to become sharded in the future.

However, Dencun’s Goerli deployment initially suffered a network split after Prysm, an Ethereum client, encountered a bug at the time of the fork.

“Prysm encountered a bug right at Goerli’s hard fork,” tweeted Terence Tsao of Prysmatic Labs, the team behind Prysm. “The bug has been identified, and a fix is currently being merged.”

Paritosh, a DevOps engineer at the Ethereum Foundation, confirmed Dencun’s finalization on Goerli roughly two hours later.

“After the fix was patched in, the validators came back online and the chain started finalizing again,” Paritosh tweeted. “All L2s can start testing EIP-4844 now.”

Dencun will next go live on the Holesky testnet on Jan. 30, before going live on mainnet come Feb. 7 — assuming no major issues are encountered beforehand.

Scalability gains

Dencun is expected to significantly reduce the fees associated with transacting on Layer 2, allowing L2s to compete with alternative Layer 1s on fees while inheriting Ethereum’s robust security layer.

A recent increase in on-chain activity has driven up Layer 2 transaction costs, with gas fees up between roughly 100% and 200% since mid-October on leading L2s Arbitrum, OP Mainnet, ZkSync Era, Base, and Linea.

Unlike calldata, the blob data introduced by Dencun do not compete with Ethereum transactions for gas usage, significantly reducing the blockspace needed to process transactions on L2.

In an appearance on The Defiant Podcast, Carl Beekhuizen of the Ethereum Foundation described the cost of storing data on-chain as the primary bottleneck restricting the scalability gains available at Layer 2.

“If you scale to thousands and thousands of transactions, then all of a sudden it costs a lot just to [store the data] on-chain,” Beekhuizen said. “The idea behind Danksharding and EIP-4844 is to provide really cheap data storage… so the L2s can provide cheap transactions to their users.”

Linea, the upstart Layer 2 from Consensys, announced it will host in-person events across 21 major cities to celebrate the upgrade and prepare developers for the post-Dencun landscape.

“EIP-4844 introduces a new way to store data on Ethereum that significantly reduces storage costs,” Linea said. “Eliminating that storage cost reduces Linea’s gas costs, and this is a big win that affects all L2s, dApps and teams that build on them.”