This is a very small update that only fixes the error code 0x80004005 when enabling Developer Mode on the “For Developers” settings page, if your PC is using a non-EN-US language. Windows 10 build 14390 contains only one known issue regarding a problem with Hyper-V firmware that affects the ability to boot Windows Server 2016 Tech Preview 5 virtual machines using secure boot. On Windows 10 Mobile build 14390 there is nothing new, and the operating system continues with Voice Recording option not working properly for Call Recording. Users may get locked out of their phones entering the PIN twice using Wallet. Microsoft is testing a new backup format for mobile devices that reduces the size stored on OneDrive. If you do a backup with the latest update, and back to the production release, then the Start layout won’t be preserved. Microsoft is listing the complete list of fixes and known issue for build 14390 at the Windows Blog. Windows 10 build 14390 for PC and Mobile is available immediately through the Fast ring. The new preview download and install automatically, but you can always force the update from Settings > Update & security > Windows Update and clicking the Check for updates button. All content on this site is provided with no warranties, express or implied. Use any information at your own risk. Always backup of your device and files before making any changes. Privacy policy info.