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Article Id 194754
Custom VM might fail to activate if custom VM is not configured properly or does not meet the requirements.
This article provides check list to investigate it.

-Run Virtual box and check the following settings:
Make sure Network 'adapter type' is set as per admin guide for the respective Operating system of custom VM requirement

Disable Audio driver as described in the admin guide:
Go to Audio, and uncheck the Enable Audio checkbox.
Disable USB driver as described in the admin guide:
Go to USB, uncheck the Enable USB Controller checkbox.

-Run the custom VM in Virtual-Box and make sure that Windows and Office are activated.
Example: For windows 10, Settings -> Update & security and Activation

-Disable UAC and firewall.
-Check if the Ethernet interfaces are in right order, and change the network adapter names to eth0 and eth1.
-Swap eth0 and eth1 order if necessary.
-Assign data drive to any letter other than 'D', if there is any.
-Enable Administrator account and clear the password
-autorun.bat is under 'Startup for All Users' folder. It's the starter to load launcher.bat in drive 'D', which is a CD-ROM drive that mounts an ISO file.
'\ProgramData\Microsoft\Windows\Start Menu\Programs\Startup'
     @echo off
     if not exist d:\launcher.bat (
     echo Wait for d:\launcher.bat
     rem sleep 5
     ping -n 5 >nul
     goto checker)

start d:\launcher.bat
-Get the VM UUID in Windows: 
mic csproduct get "UUID
-Shutdown the VM and exit VirtualBox program.
Get the Hardware UUID and MD5 checksum of the VM.
Replace the VM name to fit your requirement:

Example for windows WIN7X86VM
vboxmanage showvminfo $VM | grep "Hardware UUID:"
md5sum $VM
-Make sure following value matches:
wmic csproduct get "UUID"
vboxmanage showvminfo $VM | grep "Hardware UUID:"MD5SUM
- Customized image is too big that system doesn’t have enough memory. However, usually sandbox will show up a warning message and block the big clone number. User can reduce its size with Windows Disk Defrag tool.