Ubuntu-Powered Runtimes on Azure App Service for Linux: Leaner, Faster, Stronger

1 minute read • By Tulika Chaudharie • October 14, 2025

We’re updating the OS foundation for new code-based stacks on Azure App Service for Linux. Every new major version of our supported stacks will target Ubuntu going forward - this includes the new versions for .NET 10, Python 3.14, Node 24, PHP 8.5 and Java 25 - all expected to rollout in the next couple of months. Existing stacks remain on Debian and nothing changes for your current apps unless you choose to move.

Why Ubuntu?

Because we manage the OS for you, this change is about platform gains that quietly benefit your apps without adding work for your teams.

  • Builds on Debian’s ecosystem: Ubuntu inherits Debian’s rich package universe while moving faster upstream. This lets the platform adopt newer toolchains and libraries more predictably, improving compatibility and unblocking modern dependencies.
  • LTS stability with long runway: Ubuntu LTS follows a 5 year support lifecycle giving us a stable, well-maintained base to operate at scale.

What’s changing (and what isn’t)

  • Changing: New .NET 10, Python 3.14, Node 24, PHP 8.5 and Java 25 code-based stacks will run on Ubuntu images.
  • Not changing: Your existing apps stay on Debian. No forced migrations.
  • Operational parity: Deployment flows (Oryx, GitHub Actions, Azure CLI), scaling, diagnostics, and networking continue to work as before.

What this means for you

  • No action required for existing apps.
  • When creating a new app or upgrading to .NET 10, Python 3.14, Node 24, PHP 8.5 and Java 25, you’ll get the Ubuntu-based stack by default.
  • When upgrading, verify any native packages your app installs at build/start, since Ubuntu often provides equal or newer versions and names may differ.

Quick FAQ

Do I need to move now? No. Existing apps stay on Debian. Migrate only if you want the newer runtimes and platform improvements.

Will my build behavior change? Expected to be neutral-to-positive. Leaner images and fresher toolchains can reduce build and cold-start times.

Any breaking differences? None anticipated for supported frameworks. If you pin specific distro package versions, confirm availability on Ubuntu during upgrade.

By standardizing new stacks on Ubuntu LTS, we preserve Debian’s strengths while unlocking a faster cadence, long-term security coverage, and leaner images that translate to better reliability and performance—delivered transparently by the platform.

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