After deploying your new virtual appliance in your vSphere environment and powering on the virtual machine you see the following message No operating system found
No operating system found
The virtual appliances uses EFI/UEFI (Extensible Firmware Interface) as the boot loader if the boot option is set to BIOS the appliance will fail to boot as it does not support BIOS.
On the host we will need to modify the virtual machine settings and change the Boot Mode from BIOS to EFI. The below procedure is for modifying the boot option through vCenter Server using the vSphere client on version 6.5/6.7. If using a different version the procedure may vary and you will need to consult the appropriate VMWare documentation/support for further assistance.