“Macs introduced before 2012 or newer Mac devices with older versions of Apple Boot Camp or Windows Support Software drivers installed will not be able to install the May 2019 Windows 10 Feature Update.”
Those users who try to install it will get a message that reads: “Mac HAL Driver – machaldriver.sys: Your PC has a driver or service that isn’t ready for this version of Windows 10.”
The company is currently working to resolve the issue, and will make the update available to impacted users as soon as possible. No firm ETA has been given at this point. Microsoft did offer one bit of advice that may serve as a workaround for some users.
If you open the Apple Menu, go to the App Store and install all available updates. That may be enough to allow you to proceed with the latest Windows 10 installation. Apple has also chimed in on the matter and has a second possible workaround available on their support site. The workaround provides instructions on installing Windows Support Software manually.
If you’re not in a great rush for the latest version, you can skip both of those options and simply wait for Microsoft to resolve the issues and push the revised version out to you. Although, there are risks associated with doing so, as you’ll be lacking the latest security fixes for a time.
Sadly, this is but the latest in an ongoing series of problematic Windows 10 releases. In this case however, it has only impacted a small number of users. Even so, if you’re one of them, that’s small consolation.