If you are converting an Oracle VirtualBox VDI (Virtual Disk Image) to a VMDK for use with VMware ESXi, you might come across the following error:
Unsupported or invalid disk type 2 for 'scsi0:0'. Ensure that the disk has been imported
The invalid disk type 2 is typically a giveaway that the VMDK was mostly likely converted to a format that is only understood by a VMware Type 2 Hypervisor (Fusion/Workstation/Player) rather than ESXi which is a VMware Type 1 bare-metal Hypervisor.
Luckily, there is a straight forward way to convert the existing VMDK into the format that ESXi understands!
Note: While VirtualBox does offer an export appliance option which produces an OVA (Open Virtualization Archive), it fails to properly import into a VMware environment 🙁 and hence the need to work directly with the VDI images.