Microsoft has acknowledged an issue preventing Slow Ring Insider running the Windows 10 build 18356.16 to install the latest 19H1 build 18362. As a reminder, the preview build 18356.16 was offered to Slow Ring Insiders on March 19, just three days before the build 18362 made its way to that ring on Friday. However, many Insiders have reported over the weekend that this specific upgrade path has been problematic, with users being unable to install the latest build.
— Windows Insider (@windowsinsider) March 26, 2019
“After flighting Build 18362 to the Slow ring on Friday, Insiders began reporting they were unable to complete the update,” the Windows Insider team explained today. “We have discovered an issue with the Build 18356.16 (KB4494123) Cumulative Update that was preventing the update to Build 18362 from completing successfully. This issue only impacts Insiders who are on Build 18356.16 who try to update to Build 18362.”
While Microsoft is currently working to fix this upgrade path, the company has stopped offering the preview build 18362 to Slow Ring Insiders still running the build 18356.16. "Your feedback was immensely valuable in helping investigate this issue over the weekend," the team said today, adding that they'll soon post an update when this upgrade block has been removed.