So, you've been running Ubuntu on your virtual machine for a while, and now you're thinking... maybe I should try Windows Server. Or perhaps you started with CentOS and realized you actually need Debian for that specific project. Whatever the reason, you want to swap out your VM's operating system.
Here's the thing—changing an OS in a virtual machine is way easier than doing it on physical hardware. No USB drives to burn, no BIOS settings to fiddle with (well, mostly), and if something goes wrong? Just delete it and start over. That's the beauty of VMs.
Let me walk you through everything you need to know about switching operating systems in your virtual machine, whether you're using VirtualBox, VMware, Hyper-V, or any cloud platform.
Why Would You Even Want to Change Your VM's OS?
Okay, before we dive into the how, let's talk about the why. Because honestly, there are tons of legitimate reasons to swap out your VM's operating system.
Maybe you started learning Linux on Ubuntu, but now your company uses Red Hat and you need to get familiar with it. Or you've been developing on Windows and need to test how your app behaves on Linux. Perhaps you're just curious—"What's all this Arch Linux hype about anyway?"
Sometimes it's practical. Your current OS is acting weird, you've broken something beyond repair (we've all been there), or you just need a fresh start without the baggage of all those random packages you installed at 3 AM six months ago.
The point is—VMs give you the flexibility to experiment without consequences. Your host machine doesn't care what you're running in that virtual box.
The Two Main Approaches
Alright, so there are basically two ways to change your VM's operating system:
Option 1: Fresh Installation – You wipe everything and install a completely new OS from scratch. Clean slate, nothing carries over.
Option 2: Keep the VM, Swap the Disk – You preserve your VM configuration but attach a new virtual disk with a different OS.
For most people, Option 1 is what you want. It's straightforward, clean, and you don't have to worry about old configuration conflicts. Option 2 is more for advanced scenarios where you're managing multiple systems or need to preserve specific VM settings.
Let's focus on the fresh installation approach since that's what most of you are actually trying to do.
Step 1: Back Up Anything You Care About
Look, I know this seems obvious, but I'm saying it anyway because people skip this step and then regret it.
Before you nuke your current OS, make absolutely sure you've backed up anything important. Project files, configuration files, that script you wrote that you'll "definitely remember how to recreate"—back it all up.
If you're running on VirtualBox or VMware on your local machine, just copy the files to your host system. If you're on a cloud VM, download them or push them to a Git repository, cloud storage, whatever works for you.
Trust me on this—you'll be halfway through the new OS installation when you suddenly remember that one config file you needed, and by then it's too late.
Step 2: Download Your New OS Installation Image
You need the ISO file for whatever operating system you want to install. An ISO is basically a disc image—think of it as a virtual CD/DVD that contains the entire operating system installer.
For Linux distributions:
- Ubuntu: Go to ubuntu.com and grab the latest LTS version (22.04 or 24.04 as of 2026)
- Debian: debian.org has stable releases
- CentOS/Rocky Linux/AlmaLinux: These are the go-to for RHEL-like systems
- Fedora: getfedora.org for cutting-edge stuff
- Arch Linux: archlinux.org (but honestly, if you're reading this guide, maybe start with something easier first)
For Windows:
- You'll need a Windows ISO from Microsoft's website or through your cloud provider's image library
- Make sure you have a valid license key if you're installing Windows
For macOS:
- Hmmmm, this one's tricky. macOS in VMs is legally complicated and technically finicky. Apple only officially supports running macOS VMs on Apple hardware. Just FYI.
Download the ISO to somewhere you can easily find it. Your Downloads folder works fine.
Step 3: The Actual Installation Process
Alright, here's where it gets real. The exact steps vary slightly depending on what virtualization platform you're using, but the general concept is the same.
If You're Using VirtualBox:
Open VirtualBox and find your VM in the list. Right-click it and go to Settings.
Navigate to the Storage section. You'll see a storage tree with your virtual hard disk and probably an optical drive.
Click on the optical drive (it might show as "Empty" or have your old ISO attached). On the right side, you'll see a little disc icon. Click it and choose Choose a disk file. Navigate to your new OS ISO and select it.
Click OK to save the settings.
Now start your VM. Here's the key—you need to boot from that ISO, not your existing hard disk. Most VMs will automatically boot from the CD/DVD drive if there's a bootable disc attached, but if it tries to load your old OS instead, you might need to access the boot menu.
When the VM starts, immediately press F12 (or whatever key VirtualBox shows for the boot menu). Select the CD-ROM/DVD option to boot from your ISO.
The installation wizard for your new OS should start. Follow the prompts, select your language, partition your disk (usually you'll want to wipe everything and use the whole disk), and let it install.
This process takes anywhere from 10 minutes to an hour depending on the OS and your system speed.
If You're Using VMware (Workstation/Fusion):
Pretty similar to VirtualBox, honestly. Open VMware, select your VM, and go to Virtual Machine Settings (or just right-click and choose Settings).
Find the CD/DVD device. Change it from "Use physical drive" to Use ISO image file and browse to your downloaded ISO.
Make sure the "Connect at power on" checkbox is checked.
Start the VM. If it doesn't automatically boot from the ISO, you might need to enter the BIOS (usually by pressing F2 during startup) and adjust the boot order to prioritize the CD-ROM.
Then it's the same deal—follow the installation wizard, partition your disk, wait for it to finish.
If You're Using Hyper-V:
Open Hyper-V Manager and select your VM. With the VM powered off, go to Settings.
Under IDE Controller or SCSI Controller, find your DVD Drive. Set it to Image file and browse to your ISO.
Also check the Firmware or BIOS settings to make sure the DVD drive is in the boot order before the hard drive.
Start your VM and the installer should launch. If not, you might need to adjust boot order in the VM's BIOS settings.
If You're on a Cloud Platform (AWS, Azure, GCP, Oracle Cloud):
Cloud platforms work a bit differently. You don't typically attach ISOs manually. Instead, you:
Option A: Terminate your existing instance and create a new one, selecting your desired OS from their image library. This is the cleanest approach.
Option B: Some platforms let you create custom images or use marketplace images. Check your cloud provider's documentation for specifics.
For AWS specifically, you'd launch a new EC2 instance with your desired AMI (Amazon Machine Image). For Azure, you'd create a new VM with your chosen image. For GCP, you'd select a different image when creating a new instance.
The cloud approach is usually simpler because you're not dealing with ISOs—you're just picking pre-built images.
Step 4: Complete the Installation
Okay, so the installer is running. Now you just need to follow along with the prompts.
Every OS has its quirks, but generally you'll need to:
- Select your language and region – Pretty straightforward
- Partition your disk – For a fresh install, just choose "Erase disk and install" or "Use entire disk". Don't overthink it unless you have specific partitioning needs
- Create a user account – Pick a username and password you'll actually remember
- Configure network settings – Usually automatic, but you might need to set a hostname
- Wait for files to copy – This is where you grab coffee or scroll through your phone
Some Linux distributions will ask if you want to install additional software like a desktop environment, web server, or development tools. Think about what you actually need for this VM's purpose.
Windows installations are usually more straightforward—less customization during setup, more configuration afterward.
Step 5: Post-Installation Cleanup
Once the installation finishes and your new OS boots up, there's some housekeeping to do.
First, remove the ISO from your virtual CD drive. If you leave it attached, the VM might try to boot from it again next time, which is annoying.
In VirtualBox or VMware, go back to Settings > Storage/CD-DVD and either remove the ISO or set it to use the physical drive (which will be empty).
Second, install the guest additions or VMware tools. This is important. These tools improve integration between your VM and host, giving you better mouse support, shared folders, better graphics, and automatic window resizing.
- For VirtualBox: In the VM menu, select Devices > Insert Guest Additions CD image, then follow the installation prompts inside your VM
- For VMware: Install VMware Tools from the VM menu
- For Hyper-V: Most modern Windows and Linux distros already include Hyper-V integration services
Third, update your system. Your fresh OS probably needs updates already.
For Ubuntu/Debian: sudo apt update && sudo apt upgrade For CentOS/RHEL/Rocky: sudo dnf update or sudo yum update For Windows: Check Windows Update
Common Issues You Might Hit
Let me tell you about the problems people actually run into when doing this.
VM won't boot from ISO: Check your boot order in BIOS settings. Make sure the CD/DVD drive is listed before the hard disk.
Installation is incredibly slow: Your VM might not have enough RAM or CPU cores allocated. Power it off and adjust these in the VM settings before trying again.
Network doesn't work after installation: Usually means you need to install guest additions/tools or your network adapter type isn't compatible with the new OS. Try switching between NAT, Bridged, or Host-only networking in your VM settings.
Can't get past certain installer screens: Some OSes are picky about VM settings. Check online for recommended settings for your specific OS and virtualization platform combination.
Bottom Line
Look, changing your VM's operating system is honestly one of the easier things you'll do in the world of virtualization. It's just: attach an ISO, boot from it, follow the installer, done.
The beauty of VMs is that you can experiment without fear. Want to try that weird Linux distribution your coworker won't shut up about? Go for it. Takes 30 minutes to install, and if you hate it, just delete the VM and start over.
My advice? Don't overthink this. Download an ISO, attach it to your VM, boot from it, and let the installer do its thing. You'll figure out the quirks as you go, and that's honestly the best way to learn anyway.
That's what VMs are for—breaking things and starting over without consequences. So go break something. Intentionally this time.
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