Vercel Sandbox Runtimes Are Dead, Managed Images Take Over

Vercel Sandbox runtimes are deprecated, replaced by versioned Managed Images

Vercel shipped Managed Images (VMI) for Vercel Sandbox on August 10, replacing the runtime property that previously configured what a sandbox booted with. Starting with version 3 of the Sandbox SDK, new sandboxes default to vercel/sandbox/universal:latest instead of the deprecated runtime system, and the source for every image now lives in the public vercel/sandbox repository so teams can use it as-is or fork it.

What's actually in the default image

The new universal image is a bigger change than a rename. It switches Vercel's default operating system from Amazon Linux to Ubuntu — Vercel describes Ubuntu as "a lighter and more widely used system across the industry." The rolling latest tag ships Ubuntu 26.04 with Node.js 24, Python 3.14 with uv, and three coding agents pre-installed: opencode, claude-code, and codex, plus the pi agent, alongside standard CLI tooling like git, vim, tmux, ripgrep, jq, and fzf. Teams that previously had to build a custom image just to get a coding agent into their sandbox no longer need to.

Versioning and rollback

Every managed image gets a nightly release, and rolling tags — latest and the major-version tags — pick up OS and dependency updates automatically, including security patches. For teams that need a frozen environment instead, Vercel lets you pin to an image digest (SHA), which opts out of automatic updates entirely and gives you a fully immutable, reproducible sandbox.

Migration is opt-in, not forced

Existing code isn't broken by this change. The previous runtime property is deprecated but not removed, so anything already running against it keeps working. The one carve-out: Amazon Linux runtimes are not part of the new managed image catalog at all, so teams that specifically need AL2023 have to stay on the old runtime path rather than migrating to an image.

Why it matters if you run agents in Vercel Sandbox

The practical upside is fewer teams hand-rolling a Dockerfile just to get a coding agent running in an isolated sandbox — three major agent CLIs now ship in the default image. The tradeoff is the same one every rolling-release system carries: latest is convenient until a dependency bump breaks something, which is exactly what the digest-pinning option exists to prevent. If your CI depends on a specific Sandbox behavior, pin to a digest now rather than after a nightly release changes something under you.