Microsoft recently released a major update for Windows 10, known as Version 1511 (Build 10586). Initially, this update could be installed either via Windows Update, or as an upgrade or clean install by using the new 1511/10586 ISOs MS provided through its Techbench or Media Creation Tool links. MS has now removed the 1511/10586 ISOs, reverting them back to build 10240 - the original Windows 10 RTM build. The reason for this sudden reversal is unclear. Ed Bott
reports a Microsoft spokesman as saying this is a deliberate decision to make sure that installs of the 1511/10586 update are only through Windows Update; some users
say they've been told by MS that 1511/10586 has been removed because it causes problems.
Update: A direct download link to the 1511/10586 Media Creation Tool is still available here for now.