Microsoft has announced that its Azure App Service for Linux is being updated so that the foundation operating system is Ubuntu instead of Debian. Every new major version of supported stacks going forward will target Ubuntu, including .NET 10, Python 3.14, Node 24, PHP 8.5, and Java 25. All of these are expected to roll out in the next couple of months.
Microsoft’s decision to target Ubuntu has numerous benefits. Firstly, Debian’s ecosystem will still be inherited as Ubuntu is based on Debian, but it means faster upstream changes, allowing for more predictable adoption of newer toolchains and libraries.
Furthermore, Ubuntu’s LTS releases have mainstream support from Canonical for five years, two years more than Debian full support lasts. Finally, Microsoft believes that by switching to Ubuntu that it will be able to create leaner images, translating to better reliability and performance.
Microsoft said that for existing apps on Azure App Service for Linux, no action is required. They remain on Debian and there are no forced migrations. If you create a new app or upgrade to the new runtimes above, the Ubuntu-based stack will be the default instead. As for deployment flows such as Oryx, GitHub Actions, and Azure CLI; scaling; diagnostics; and networking, they will continue to work as before.
Microsoft said that build behavior is expected to be neutral-to-positive, with leaner images potentially reducing build and cold-start times. As a side note, Microsoft said that when upgrading, users should verify any native packages their app installed at build/start, as versions or names could be different on Ubuntu. For supported frameworks, no breaking differences are anticipated.
Source: Microsoft
