Sharp-eyed Insiders likely noted the big jump in build numbers from our last preview build (11102). Historically, the codebase for mobile had a different OS version than the codebase for PC because they were developed by different teams on different schedules. With Windows 10, we became one Windows team and brought these two codebases together. We started by changing the version string displayed in the UI to be consistent, which is why you saw similarly labeled builds over the past year for both Mobile and PC, but the underlying binary version numbers were still different. As part of our work getting the common codebase ready for the next release, we decided to complete that work and sync the build numbers between mobile and PC. Because the mobile codebase used higher build numbers than PC, we needed to jump ahead a bunch of build numbers to ensure updates to future builds will continue to work. So that’s why build numbers went from 11105, 11106, and 11107 to 14251.