Tor to Drop Support for Version 0.4.8 and Earlier in September 2026

The Tor Project has announced that it will discontinue support for Tor 0.4.8 and earlier releases beginning September 1, 2026, marking a significant step in the network’s ongoing modernization efforts.

The decision is intended to prepare the anonymity network for the wider adoption of Arti, the Rust-powered Tor reimplementation that developers believe will play a major role in the project’s future.

Importantly, the announcement does not affect the version number displayed in the Tor Browser itself. Most users running the latest Tor Browser releases are already using supported versions of the underlying software and are unlikely to notice any changes.

Instead, the update primarily impacts relay operators, onion service administrators, self-hosted applications, and privacy tools that embed older Tor software versions.

End of Life for Tor 0.4.8

Tor 0.4.8 officially reached end-of-life status on June 1, 2026, meaning it no longer receives security updates or maintenance. Although the Tor Project has historically attempted to maintain compatibility with unsupported releases whenever possible, developers said continuing to support the aging software would slow development and delay important network improvements.

The primary technical issue involves Tor’s directory protocol, the system responsible for distributing relay and network information to clients. In the Tor 0.4.9 release series, older features such as TAP onion keys and family lines were deprecated. However, these fields remained within directory data to preserve compatibility with older software.

Beginning September 1, these obsolete fields will be removed entirely. According to the Tor Project, eliminating the outdated information will reduce the amount of data clients must download, resulting in lower bandwidth consumption and faster bootstrapping, particularly for users on slower internet connections.

Older versions of Tor, however, still expect these fields to exist. Once the deprecated fields disappear, Tor 0.4.8 and earlier releases will no longer be able to properly process directory information, effectively preventing them from connecting to the network.

Arti Development Driving Changes

Another major factor behind the decision is Arti, the Tor Project’s Rust-based implementation designed to gradually replace portions of the existing Tor codebase. Rust has gained popularity within the security community because of its built-in memory safety protections, which help reduce vulnerabilities related to memory corruption and software bugs.

The Tor Network Team said future integration of Arti-based directory authorities will become significantly easier if the network no longer needs to maintain support for legacy protocol features.

Removing obsolete functionality also reduces development complexity and allows developers to focus on improving performance, security, and maintainability. The transition to Arti represents one of the most important architectural changes in Tor’s history.

Downstream Projects Urged to Upgrade

The Tor Project commenced the outreach to downstream projects as well as maintainers who may still distribute older Tor versions. Developers are encouraging the community to help identify applications, embedded systems, and privacy tools that continue to rely on unsupported releases.

Advise organizations running Tor relays, onion services, self-hosted platforms, or Tor-based applications to verify their software versions immediately. Administrators should upgrade to the Tor 0.4.9 series or newer before the September deadline.

Failure to update could result in relays falling offline, onion services becoming unreachable, or applications losing connectivity to the Tor network altogether.

Balancing Privacy and Modernization

The decision highlights the ongoing challenge faced by privacy-focused projects: maintaining compatibility while continuing to evolve. Tor remains one of the world’s most widely used anonymity networks, routing internet traffic through thousands of volunteer-operated relays to help users protect their identities and avoid surveillance.

The Tor Project has consistently prioritized user privacy. Recently, it made a bold move by purging Mozilla’s AI components from the Tor Browser to prevent potential data leakage.

Many secure messaging platforms, privacy-focused operating systems, research tools, self-hosted services, and security applications embed the software beyond the Tor Browser.

While some operators may face short-term challenges upgrading older systems, the Tor Project argues that retiring outdated software is necessary to improve efficiency, simplify future development, and support the next generation of anonymity tools through the Arti project.

For most users, the transition should occur seamlessly in the background as long as they keep their software up to date.