Default boot device missing or boot failed. - Microsoft Community
Lenovo Y540, keep getting this error every 2 or 3 weeks, Default Boot Device Missing. After restarting, gives a BSOD "WHEA Uncorrectable Error" then after restarting again, everything is fine. Both SSD
SOLVED] Boot Device Missing | How to Fix an Inaccessible Boot Drive
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Fixed – Default Boot Device Missing or Boot Failed on Lenovo/Acer
Default Boot Device Missing or Boot Failed message on Lenovo Yoga 920! Please help!!
Default Boot Device Missing or Boot Failed" Error - Windows 8 & 10 - Lenovo Support US
Lenovo Ideapad, Acer, Default Boot Device Missing or Boot Failed, Error Windows 7, 8, 10, 11 - YouTube