In a bizarre decision, Microsoft has pulled their Upgrade Advisor app, which means that Windows 8.1 users are out of luck if they still haven’t upgraded to Windows 10 Mobile. This follows the news that only 13 Windows Phone devices have been given the privilege of receiving the Creators Update. While Microsoft claims they are not killing Windows 10 Mobile, all of this is evidence to the contrary. Microsoft recently culled the number if Windows phones that could upgrade to newer versions of the OS with the release of the Creators Update, and now the firm has pulled the Upgrade Advisor app that was necessary for Windows Phone 8.1 users to make the jump to Windows 10 Mobile. Aside from that, some Windows 10 Mobile users (but not all) are now reporting that the Windows Insider app no longer offers new builds for devices on 8.1, which means that if those Insiders on newly unsupported phones which originally shipped with Windows 8.1 decide to downgrade, they may no longer be able to upgrade their devices to any build of Windows 10 Mobile – supported or no.