Netlify has upgraded its default build image from Ubuntu Linux 14.04 LTS (codenamed "Trusty Tahr") to Ubuntu Linux 16.04 LTS (codenamed "Xenial Xerus") as it reaches its end of life in April 2019, requiring changes to the operating system version on their build images. This change allows for more flexibility and testing capabilities, enabling the company to roll out new features and improvements to all new sites without affecting existing ones. Existing sites can still run on the "Trusty" image, but users can now upgrade to the newer "Xenial" image with a single click in their Build & deploy settings page. The updated build infrastructure paves the way for future innovations and improvements.