While trying to start a virtual machine the first time, the error, "VirtualBox - No Bootable medium found. System halted." was displayed on the VM window.
This error means that the operating system kernel to boot the virtual machine was not found. It was rectified with the following steps.
- Download an operating system from the Internet. A copy of Ubuntu Server 20.04.3 was downloaded. With this, a copy of the operating system to be used for booting the VM became available on the hard disk of the host system.
- Now, we need to tell VirtualBox that the VM should be booted with this operating system. Click on the "Storage" in the settings for the VM. Under the first Controller: IDE, click on "Empty". Here, choose the downloaded operating system image. Click OK.
- Click the green arrow in the "Start" tab for the VM.