The Dencun upgrade is designed to reduce costs for layer-2 transactions and data availability on Ethereum, in the blockchain's biggest changes since April 2023.
The upgrade was successfully deployed Wednesday on the third of three test networks.

Ethereum developers set a target date of March 13 for its long-awaited Dencun upgrade during a bi-weekly coordinating call on Thursday, officially triggering the countdown to the blockchain's biggest changes since April 2023.

The Dencun upgrade is primarily known for its "proto-danksharding" feature, which is supposed to reduce costs for transactions on auxiliary "layer-2" networks built atop Ethereum, by providing a dedicated space for data storage.

Latest News: Ethereum Finalizes 'Dencun' Upgrade, in Landmark Move to Reduce Data Fees

The decision was communicated during the all core developers consensus layer call 127 – just one day after the upgrade was successfully added to the Holesky testnet, the third of three test networks, without any hiccups.

"It's great to see years worth of effort finally being scheduled for Ethereum mainnet," said Parithosh Jayanthi, a devops engineer at the Ethereum Foundation, to CoinDesk over Telegram.

The precise moment of the Dencun upgrade on the main Ethereum network – also known as a "hard fork" – will trigger when the blockchain reaches slot 8626176, occuring at 13:55 UTC on March 13.

The date needs to be ratified by developers and confirmed via the open-source software platform GitHub.

Dencun will enable a new type of transaction class called “proto-danksharding,” which will help reduce the costs of transactions for rollups, through the introduction of data “blobs,” a new category for storing data.

Ethereum Data Availability

It’s also supposed to help reduce the cost of data available on Ethereum, thus making projects like Celestia, Avail, and EigenDA more attractive.

Developers have run through three tests in order to ensure that Dencun will run smoothly on mainnet, culminating in this week's deployment on the Holesky testnet.

Proto-danksharding is the first iteration of a technical feature, known as “danksharding,” that developers are working towards implementing to scale the blockchain.

The inked-in date for Dencun means that the upgrade will go live later than the developers had initially planned for. They originally targeted it for the end of 2023, but due to technical delays, the upgrade was pushed to early 2024.

As part of the Ethereum roadmap, developers are already planning their next hard fork, Prague/Electra, which could potentially include “Verkle Trees,” a new type of data structure that should help nodes storing large amounts of data “without losing the ability to validate blocks.”

Sharding Dencun Ethereum Upgrade Rollups rollup layer 2 data availability

Margaux Nijkerk

Margaux Nijkerk reports on the Ethereum protocol and L2s. A graduate of Johns Hopkins and Emory universities, she has a masters in International Affairs & Economics. She holds a small amount of ETH and other altcoins.