https://www.techradar.com/news/windows-10-spring-creators-update-has-been-delayed-by-a-serious-bug

As you might well have noticed, Microsoft’s next big update for Windows 10 – thought to be called the Spring Creators Update – didn’t emerge yesterday, and has apparently been delayed due to the presence of a significant bug.

As we previously reported, the Spring Creators Update was expected to debut on April 10, but according to sources who spoke to Windows Central, Microsoft found a ‘blocking bug’ over the past weekend which needs to be fixed before the big rollout begins.