
On both of the flash drives when I right-click on the drive the "Mark Partition as Active" option is greyed out. Then I decided I'd like to mark one of them as Active so I could set it up as a bootable installation flash drive. Both of them are set up as MBR drives so there’s no issue there. Why is Mark Partition Active greyed out in Disk Management? Hi, Yesterday I used Disk Management on a couple of 16GB USB flash drives to create a New Simple Volume and ran a Full Format on them both as FAT32 with a single partition. why is Mark Partition as Active greyed out? Let’s keep reading.

However, many users reported that they can't Mark Partition as Active in Disk Management.

It can be used to set as the bootable partition on computers. The active partition is the main partition on the hard disk, which contains the operating system, boot sector, and other important bootable files.
