These weren't just builds launching earlier than expected, they were builds never meant to reach the public. After learning about the inconvenience that the accidental release has caused to some users, Sarkar apologized by saying, "We apologize for this inconvenience and thank you for being a Windows Insider".
This problem happened due to an inadvertent deployment to the engineering system that controls which builds/which rings to push out to insiders. In the case of mobile devices, the update might end up bricking them.
Microsoft's Dona Sarkar has confirmed in a blog post that they will not be releasing new builds for Windows 10 and Windows 10 Mobile this week. Also, users can roll-back to previous Insider builds via Settings Update & Security Recovery.
The situation is potentially much worse for anyone who received the rogue mobile build. We would like to reveal that builds from wrong branch and devices were rolled out to Windows 10 Mobile Devices.
As discovered late a year ago, Home Hub is meant to be a feature for making Windows 10 devices a central clearinghouse in families' homes.
Windows XP has been one of the most widely used versions of Microsoft's desktop operating system which was affected by the WannaCry ransomware, and as compared to the new release, it had been in the need of an emergency patch from the parent company to keep systems secure and block infections. Users who have downloaded the update but not installed will still need to do a device reset in the system settings. Once the re-flash is complete, you can join the Windows Insiders program again. My monitoring of social media showed that quite a few users were unable to stop their own download/install processes with this incorrect build and now had mobile devices stuck in a boot loop.
This is why you only put Windows 10 Insider preview builds on secondary PCs, folks. The highlight of this mishap being that the said builds were not only pushed to Fast Ring (or any other Ring) Insiders but was released to everyone running the recently debuted Creators Update. It can be safely said that the internal build 16212 that was released was not even an alpha update.