In Manjaro I have an Oracle VM Virtual Box. and there is another Linux in it, I launch this Linux and on the black screen the inscription No bootable medium found system halted after that it does not work I can not acquire root rights and enter the Linux command line on the VM Please tell me what to do Thank you in advance
No bootable medium found
indicates exactly that - there seems to be no (virtual) harddrive to boot from
In the settings for that machine you checked whether there is everything in order?
For instance:
System Settings → Boot Order: there should be a Hard Disk
and
Storage: there should be at least one Controller to which your virtual harddrive with the linux system on it is connected
Support questions for virtualbox are better asked at the appropriate place:
https://forums.virtualbox.org/
exactly as leebut said: