Quick Fixed: Mark Partition as Active Greyed out on Windows 10/8/7

February 25, 2019

In Disk Management, only one primary partition can be marked as active. If there is no primary partition or you mark partition as active mistakenly, you will find mark partition as active greyed out. To fix it, I recommend you AOMEI Partition Assistant.

What is the active partition?

The active partition is a primary partition on your hard drive, which can be set as the bootable partition and contains operating system. For example: if your computer is Microsoft Windows, the active partition is a partition contains Windows. 

At the same time, there is only one primary partition can be set as active partition or bootable partition on each hard drive. If you set one primary partition as active partition, you cannot set another partition on this drive as the active partition.

Why mark a partition as active?

When you boot your computer, BIOS will look for an active partition among the primary partitions first. Then, the boot sector located at the beginning of the active partition will run the boot loader (an operating system tool) to download the operating system boot files. After that, you can boot your computer as usual.

Thus, if you want to boot your computer, you need an active partition. At the same time, you still need to pay attention to the following things.  

1. The active partition must have a boot sector created by the operating system.

2. The active partition should contain the boot loader and boot files for the OS. Furthermore, the boot loader must clearly get the location of the OS on the physical hard drive.

3. The actual operating system has to be located in the correct spot on the hard drive

Why does mark partition as active greyed out?

1. Only primary partition can be marked active.

If you want to boot your computer, you must need both operating system and boot files. However, both of them can only be saved on the primary partition instead of a logical partition. Thus, if there is no primary partition, you will find the problem: mark partition as active greyed out.

2. Only one primary partition can be marked active. 

On a hard drive, you are only allowed to mark a primary partition as active. If you already mark one primary partition on the hard drive, Disk Management will unmark partitions as active.                                                

Mark Partition as Active Greyed Out

Fixed: mark partition as active greyed out on Windows 10/8/7

You can clearly see from above, only one primary partition can be set as active. In Disk Management,if there is no primary partition or already has an active partition, you will find you cannot mark partition as active on Windows 10/8/7. 

To fix it, I recommend you AOMEI Partition Assistant. With it, everything becomes easy. If there is no primary partition, you can convert logical partition and mark the primary partition as active. If you mistakenly mark a  partition as active, you can directly mark another partition.

Situation One: There is no primary partition

Convert logical partition to primary partition

Step 1. Download AOMEI Partition Assistant professional, install and launch it.

Step 2. Click the logical partition you want to convert, then select Advanced and Convert to Primary.

Convert Logical to Primary

Step 3. Click OK to confirm the pending operation

Step 4. Preview the final result, then click Apply and Proceed.

Set a primary partition as active

Step 1. Right-click the primary partition you want to mark as active, select Advanced and Set Active Partition.

Set Active Partition

Step 2. Click OK to ensure the pending operation.

OK-Set-Active-Partition

Step 3. Preview the result, then click Apply and Proceed. At last, you will see an active partition as shown in the following picture.

Apply

Situation two: Mark a partition as active mistakenly

Set the right primary partition as active

Step 1. Click the partition you want to mark as active, then select Advanced and Set Active Partition.

Set Active Partition Right

Step 2. Click OK to ensure the operation.

Step 3. Preview the result, then click Apply and Proceed.

Summary

In Disk Management, only primary partition can be marked as active. If there is no primary partition or you mark partition as active mistakenly, you will find mark partition as active greyed out. 

To fix it, I recommend you AOMEI Partition Assistant. It can easily solve the problem:  mark partition as active greyed out. If there is no primary partition, you can convert logical partition to primary partition. If you mistakenly mark a partition as active, you can mark the right partition as active. 

AOMEI Partition is very useful, which can solve various problem, such as Extend Volume Is Disabled , Windows 10 Hard Drive Llimit, Selected Disk is GPT Partition Style