A few days ago, Microsoft released Windows 10 Build 18356.16 with KB4494123 to Insiders in the Slow Ring. There are a number of issues that caused Microsoft to pull the build.
The update didn't include any new feature. Windows 10 Build 18356 represents the next Windows 10 version, currently known as version 1903, April 2019 Update, or 19H1. Here's the change log for KB4494123:
UPDATE 3/19: Hello Windows Insiders, we have released Windows 10 Insider Preview Build 18356.16 (KB4494123) to Windows Insiders in the Slow ring. This Cumulative Update is a little bit bigger as it is designed to help us test our servicing pipeline with larger updates. This update contains nothing new. We simply updated the version numbers of several components in the OS.
UPDATE 3/15: Hello Windows Insiders, we have released Windows 10 Insider Preview Build 18356.1 (19H1) to Windows Insiders in the Slow ring.
[ADDED 3/13] IMPORTANT NOTE: Some Windows Insiders may have had their devices opted out of receiving new builds after installing Build 18356. You can check your settings via Settings > Update and Security > Windows Insider Program. If your device was opted out, you will need to click the “Get Started” button and opt your device back into flighting. If your Windows Insider settings look correct, no action is required.
You will find the full change log for build 18356 HERE.
Now, Microsoft is stopping redistribution of the update. They have provided the following statement.
Over the last couple of weeks, Insiders in the Slow ring have been receiving new 19H1 builds in addition to also receiving Cumulative Updates. After flighting Build 18362 to the Slow ring on Friday, Insiders began reporting they were unable to complete the update. 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. THANK YOU to Insiders who reported feedback on this in Feedback Hub and upvoted – your feedback was immensely valuable in helping investigate this issue over the weekend! The team is currently working on a fix now. In the meantime, Build 18362 will no longer be offered to Insiders who are on Build 18356.16, so Insider PCs don’t continue to try and take Build 18362 and fail.
Microsoft promises to resume the delivery of build 18356 after they fix the issue.