In-depth essays · #22 / 50 · Architecture, Consensus & Upgrades
Ethereum’s Upgrade Chronicle: How Dencun (2024), Pectra (May 2025), and Fusaka (Dec 2025) Reshaped the City
From the birth of EIP-4844 blobs to EIP-7702 smart wallets, validator consolidation, and PeerDAS
Ethereum is not a static monument—roughly once or twice a year, the protocol upgrades its roads and rules without stopping traffic. Over the past two years, three landmark hard forks—Dencun, Pectra, and Fusaka—transformed both downtown L1 and every L2 district.
1. Why Upgrades Carry Star-and-City Names
Because Ethereum pairs an Execution Layer (named after Devcon host cities) with a Consensus Layer (named after stars), combined upgrades blend both names: Dencun (Deneb + Cancun), Pectra (Prague + Electra), and Fusaka (Fulu + Osaka).
2. Dencun (March 2024): EIP-4844 Blobs Ignite the L2 Boom
Dencun introduced EIP-4844 blobs (targeting 3 blobs per block, max 6), giving rollups a dedicated temporary data lane and slashing L2 fees by an order of magnitude overnight.
3. Pectra (May 2025): EIP-7702 Smart Accounts, 2,048 ETH Validators, and More Blobs
Pectra delivered three major upgrades at once: EIP-7702 brought smart-account batching and fee coverage to standard EOA wallets; EIP-7251 raised the maximum effective balance per validator from 32 ETH to 2,048 ETH (letting operators consolidate thousands of keys and compound rewards); and EIP-7691 doubled target blob capacity from 3 to 6 (max 9) per block.
4. Fusaka (December 2025): PeerDAS Unlocks Scalable Data Availability Sampling
Fusaka shipped PeerDAS (Peer Data Availability Sampling), allowing nodes to verify that blob data is available by sampling small erasure-coded slices rather than downloading every byte—expanding blob capacity for L2 districts while keeping home node bandwidth lightweight.
Related districts in the city
Related glossary terms
This essay is an explainer written to help you read the city; it is not investment advice. Facts on this page are as of 2026-10 and may change. If you spot a mistake, please tell us through the contact page.