Throughout 2017, the WordPress team have been building key new features using the React framework, developed by Facebook.

However, React has had problems licensing issues, In mid-September, Matt Mullenweg announced that the WordPress team, and Automattic, were dropping the React framework:

the Gutenberg team is going to take a step back and rewrite Gutenberg using a different library. It will likely delay Gutenberg at least a few weeks, and may push the release into next year

This was big news for WordPress, and a notable set-back for the project's development.

Thing everything changed again.