You can convert the disk to VHD format using Hyper-V Manager or the convert-vhd cmdlet.

The VHDX format is not supported in Azure, only fixed VHD.

Please see also General Linux Installation Notes for more tips on preparing Linux for Azure.

For instructions, see Install the Hyper-V Role and Configure a Virtual Machine. vhd files, for example a virtualization solution such as Hyper-V. This article assumes that you have already installed a CentOS (or similar derivative) Linux operating system to a virtual hard disk.

Prepare a CentOS 7.0+ virtual machine for Azure.

Prepare a CentOS 6.x virtual machine for Azure.

Learn to create and upload an Azure virtual hard disk (VHD) that contains a CentOS-based Linux operating system.

Choose replace existing linux in one of the following screens.Applies to: ✔️ Linux VMs ✔️ Flexible scale sets.

Provide a server name and a root password.

The next screen will ask you to discard data - click yes.Check the basic storage devices button.Click start (the green arrow) - this will start the installation process in graphical mode.In Attributes section browse to your iso by clicking the cd icon. Mount the operating system disk image of Cent OS minimal that you have downloaded earlier: select storage tab, select Empty in Storage Tree frame.File location and size: leave 8 GB for the size.Storage on physical hard drive: Dynamically allocated.

Choose the Name of you choice, Linux for Type, Red Hat 64 bit for Version.To get an image of CentOS go here and choose the version you want (I went for 6.5) by clicking on x86_64 then pick one of the mirror servers for downloading the desired image (my choice was CentOS-6.5-x86_64-minimal.iso).

Download virtualbox for centos 6.5