Given that this error is a known issue that the developers at Parallels have publicly acknowledged and fixed, the primary and most straightforward solution is to .
If the error persists despite using an updated Parallels and a USB drive, the culprit is almost certainly the unattended.iso file you built. The file may be corrupted or configured incorrectly.
The hypervisor loses track of the virtual hardware mapping or suffers from conflicting IDE/SATA/SCSI controller states.
If installing on hardware, use Rufus to create your bootable media. windows 11 cannot connect unattendediso to cd dvd 2 better
Open Device Manager (right-click Start button > Device Manager). Expand DVD/CD-ROM drives . If you see a grayed-out or faded “CD/DVD 2,” right-click it and select Uninstall device . Reboot Windows 11.
Which are you using? (e.g., VMware Workstation, ESXi, Hyper-V, or VirtualBox)
If the ISO is located on a network drive or a virtual disk, the system might fail to mount it. Move the autounattend.iso file to a local drive (e.g., C:\isos\ ) on your physical machine before attaching it to the virtual machine. Summary Checklist Potential Cause Create VM manually ("Install OS later"). Wrong Drive Letter Remove floppy/second CD drive in VM settings. Corrupt ISO Recreate autounattend.iso using Imgburn. SCSI Driver Missing Switch CD/DVD drive to IDE controller. Given that this error is a known issue
Add a new , and add the DVD drive under the IDE controller. 2. Use PowerShell to Force Mount Sometimes, a manual PowerShell mount is more reliable: powershell
that might be using the ISO file on the host machine.
| Feature | UnattendedISO (Legacy) | Fix 1 (Native PowerShell) | Fix 2 (WinCDEmu) | | :--- | :--- | :--- | :--- | | | ❌ No | ✅ Yes | ✅ Yes | | Mount as specific “CD/DVD 2” | ❌ Fails | ✅ Via Disk Management | ✅ One-click | | Security Warnings | High (unsigned driver) | None | None | | Hyper-V / WSL2 Compatible | ❌ Breaks | ✅ Yes | ✅ Yes | | Requires Installation | Yes | No (built-in) | Yes (lightweight) | The hypervisor loses track of the virtual hardware
Ensure your virtual machine has a Virtual TPM (vTPM) module enabled and is configured for UEFI boot mode instead of Legacy BIOS.
The host system or another application has a lock on the unattended.iso file, preventing the virtual machine from reading it.