1] Check the boot sequence and boot mode This is one of the important solutions to fix this Default Boot Device Missing or Boot Failed problem on your Windows 11/10 system.

A quick and easy to way to fix How To Fix Inaccessible Boot Device Error on PCs running on Windows 8, Windows 10, and Windows 11 OS.

Read: Fix Automatic Startup Repair not working 2] Verify the boot order If you are using a dual boot system on your computer, it is highly recommended to verify the boot order.