Thank you for coming Microsoft MECM Q&A forum.
==>"Failed to make volume C:\ bootable. Please ensure that you have set an active partition on the boot disk before installing the operating system."
When in BIOS mode, you can only install the OS to a BIOS partition scheme. If you want to install the OS as a UEFI scheme, you need to boot to UEFI. This is because the task sequence will only create boot systems that match the current mode.
Please help check your format and partition task and make sure that you've set the proper partition as active. Copy a default format and partition task from a Wizard generated task sequence if you need to.
Thanks for your time.
If the response is helpful, please click "Accept Answer" and upvote it.
Note: Please follow the steps in our documentation to enable e-mail notifications if you want to receive the related email notification for this thread.