KB4474419 will not install

But Windows cannot boot other operating systems. It would make it impossible to boot other operating systems I have installed. I have to use a boot loader that can load Windows, Linux and FreeBSD.

I succeed with the update.

Go in BIOS, set the windows disk as first boot device.

Let the windows update reboot the computer as it likes.

When the windows update succeed, reboot to BIOS to set the "GRUB" (boot loader) disk back as the first boot device.

You get your multi-boot back to normal.

Well, if you are in my case, have one disk dedicated for Linux, and one disk dedicated for windows.

I have one disk for all 3 operating system that my system boots. So the disk that boots Windows is actually the first (and only) disk that is used to boot.

A risky solution could be to overwrite the bootloader with the Windows's boot loader.

Make the windows update.

Then overwrite the windows boot loader back with the linux boot loader.

If you know what you're doing.

I can do it, but I still call it playing with fire, and I don't understand why this interferes with this particular update... Thank you for the suggestion. I think I will wait for some time before I get upset enough to actually do it...