Microsoft is now testing Windows 10 build 17616 internally. The new Windows 10 Redstone 5 build 17616 (10.0.17616.1000 rs_prerelease.180228-1619) was compiled on Fab 28, 2018.
Windows 10 Spring Update preview build 17112 is now available for Insiders. The new build comes with various bug fixes and improvements. However, there are two issues with the Windows Mixed Reality on this build.
Windows Mixed Reality runs at a very low frame rate (8-10fps) that could result in some physical discomfort and there are multiple crashes at startup that will cause Windows Mixed Reality to not work.
The ISO files for Windows 10 build 17112 are also now available for download. You can download it from the link below.