Some Toshiba SSDs cause an incompatible error when updating Windows 10 April Update
There are also other operational issues that Microsoft does not mention. However, they are also looking for causes and ways to overcome them. If the update fails, you can return to using version 1709 after Microsoft fixes it.
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Why Intel killed the BIOS, switched to UEFI?
The new update fixes many bugs on Windows 10 April 2018 Update but causes a more serious error