Default Boot Device Missing or Boot Failed. Insert Recovery Media and Hit any key Then Select 'BootManager‘ to choose a new Boot. Device or to Boot Recovery Media

Hello,

I was just about to perform a full backup when this error message appeared.

Default Boot Device Missing or Boot Failed.
Insert Recovery Media and Hit any key
Then Select 'BootManager‘ to choose a new Boot.
Device or to Boot Recovery Media

Can anyone give me some advice on how to fix this problem?

QubesOS Version R4.3.0
Kernel: 6.18.15-1
Xen: 4.19.4

Software: Backup Qubes