After an extended period of testing in the Release Preview ring, Microsoft has finally started rolling out the May 2019 Update to Windows 10 users, albeit in a "measured and throttled" way. In the meantime, users of Sophos Endpoint Security and Control and Sophos Central Endpoint Standard/Advanced have been advised to remove the "offending" Windows updates (KB4499164 or KB4499165) for the AVs to work, and delay the patching until Sophos delivers the update that will fix the conflict.
Microsoft is known to keep its users updated with the latest version of Windows update patches, which is why everyone prefers it. This makes a great change from previous Windows 10 feature updates and means that uptake of the May update is likely to be severely impeded. Microsoft Windows 10 users all over the world are facing the same issue after installing the new Microsoft update.
There is, however, a catch.
I suggest that you wait with the installation of the May 2019 Update for Windows 10 unless you really, really need it. Things should settle down after a month or two, and you don't risk running into another updating issue that you may spend hours or even days fixing.
To be generous to Microsoft, privilege escalation flaws are a dime a dozen in Windows: the software giant patches them every month in its operating system.
For those, who have still not updated, the best option is not to install the new Microsoft update. From this window, click on Troubleshoot Advanced options More recovery options Startup settings Restart now. You can check which update blocks are in place here.
Note that Microsoft limits availability at this point and that the company is "slowly throttling up" the availability while it is monitoring data and feedback. Because of Microsoft's focus on providing the most up-to-date, secure experience, the April 2018 Update (version 1803) will reach end of service on November 12, 2019 for both Home and Pro editions, Microsoft said.
During the system restore process, Windows temporarily stages the restoration of files that are in use. In any case, our advice holds: Pick a day to process the updates, and schedule them for a time where your PC will run unattended.