https://www.theregister.co.uk/2018/04/17/waiting_for_windows_10/

Windows 10 Springwatch – as it shall henceforth be known – has entered its second week and Microsoft has dropped the first clue as to what caused the delay: bugs.

Though Microsoft has never actually confirmed a release date or name for the elusive Windows 10 Spring Creators Update (aka version 1803), many expected it to arrive on 10 April's patch Tuesday, with build 17133 hitting the Release Preview ring of the Windows Insider programme.