Arbitrum docsArbos releases
Overview of ArbOS software releases and the release notes for each version, from ArbOS 11 to ArbOS 61 Elara.
ArbOS software releases: Overview
Overview of ArbOS software releases for Arbitrum, including upgrade requirements and the relationship between Nitro and ArbOS versions.
ArbOS 61 Elara
Learn about the ArbOS 61 Elara release and upgrade requirements for Arbitrum chain owners and node operators.
ArbOS 51 Dia
Learn about ArbOS 51 Dia release, including Fusaka upgrade support, new EIPs, bug fixes, and upgrade requirements for Arbitrum chain owners and node operators.
ArbOS 40 Callisto
Release notes for ArbOS 40 Callisto, shipped via Nitro v3.6.5, building upon ArbOS 32 Bianca with new features and requirements.
ArbOS 32 Bianca
Release notes for ArbOS 32 Bianca, the canonical Bianca release shipped via Nitro v3.3.1, including Stylus fixes and optimizations.
ArbOS 20 Atlas
Release notes for ArbOS 20 Atlas, shipped via Nitro v2.3.1, adding support for Ethereum Dencun upgrade and blob data.
ArbOS 11
Release notes for ArbOS 11, shipped via Nitro v2.2.0, including Shanghai upgrade EVM changes and upgrade requirements.
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