By Dervish / Last Updated April 25, 2022

The Symptom

When one of your partitions, especially the system (C) partition, in Windows Server 2016 is in low disk space, you may want to extend the partition with the built-in tool Disk Management that is equipped with the “Extend Volume” feature. Unfortunately, when you attempt to extend the C drive, you are most likely to find out that the Extend Volume greyed out in Windows Server 2016. What caused this problem and how to fix it effectively? The following content will explain both of them clearly.

Why is Disk Management Extend Volume greyed out in Server 2016?

Although Disk Management offers “Extend Volume” function, it can only work under some specific conditions. Namely, when your disk partition structure meets the conditions, then you can successfully extend the selected partition via this feature. Otherwise, the “Extend Volume” option will be grayed out.

1. The extend volume or shrink volume feature only works with NTFS file system. If the partition you want to extend is not formatted with NTFS, the Extend Volume option will be grayed out.

Extend Partition 1

2. It is unable to extend volume in Windows Server 2016 when there is no contiguous unallocated space or free space on the hard drive.

Extend Partition 2

3. There is contiguous unallocated space, but it is on the left of the partition to be extended. The unallocated space should be on the right adjacent side.

Extend Partition 3

4. If you want to extend a primary partition, the Extend Volume will not be available when there is a free space (in the extended partition) instead of unallocated space after the partition needs extending. Similarly, it will not work when you try to extend a logical partition but unallocated space is in the way.

Extend Primary Partition

How to fix “Extend Volume greyed out” in Server 2016?

Based on the possible reasons for which that you are unable to extend volume in Server 2016, generally, the following two methods can help solve this problem.

1. Convert FAT32 volume to NTFS before extending

To change the file system of the target volume from FAT32 to NTFS, you can use Command Prompt.

Step 1. Find the letter of partition you want to convert in Windows File Explorer or Disk Management.

Step 2. Press the Windows logo key + R to open the Run dialog box.

Step 3. Input “cmd” and press Enter to open the command prompt window.

Step 4. At the command line prompt, type convert [drive letter]: /fs:ntfs. For example, if the letter of the drive you want to convert is D, you would type ”convert D: /fs:ntfs”

Cmd Convert Fat32 To Ntfs

Please note that there is no corresponding commands to convert NTFS back to FAT32. To do so, you have to back up required files and reformat this drive again, or turn to a “NTFS to FAT32 Converter”.

2. Delete the partition behind the target volume

When there is no unallocated space on the right adjacent side of the aim partition, the "Extend Volume" option will be unclickable. Since Disk Management does not allow you to move partition, you need to delete the partition that locates right behind the partition you wish to extend. Then the “Extend Volume” will be available in Disk Management. But before that, you should make sure you backup the partition you will delete.

Better way to evade "Extend Volume Greyed Out" in Server 

Above methods can help solve "Extend Volume" greyed out issue in Server 2016, they are easy to cause data loss. So here we will share you guys with a better solution. That is making use of AOMEI Partition Assistant Server. This third-party server partition manager is compatible with Windows Server 2022/2019/2016/2012/2008/2003.

Much more advanced than Windows Server Disk Management, it is able to extend partitions formatted with either FAT32 or NTFS. Besides, it comes with "Move Partition” feature, allowing you to move the partition between the unallocated space and the target partition to make them adjacent so that you can extend the partition successfully. It doesn’t distinguish free space and unallocated, so you can extend a partition with free space or unallocated space.

Besides, it provides the ability to convert primary partition to logical without losing data, and vice versa. What’s more, with the ability to merge partitions, you can easily extend partition in any case without losing data. Let’s see how it works:

PS.: You can download the AOMEI Partition Assistant Demo version for a free trial. It allows you to preview all functions and simulate all operations.

Download Free Demo Server 2022/2019/2016/2012/2008/2003
Secure Download

1. Install and launch AOMEI Partition Assistant Server. In the main interface, right click the partition and select the option "Merge Partitions".

Merge Partitions

2. In the pop-out window, check the adjacent partition or unallocated space to be merged.

Choose Unallocated Space

3. Preview the partition layout. If it doesn’t meet your needs, you can just click Undo to go back to any step you want. When everything is perfectly checked, Click Apply to apply all the changes.


Most importantly, if there is no unallocated space on the hard drive, you can also directly assign some free space from one drive to another via the “Allocate Free Space” function.

Allocate Free Space Mbr Disk


In conclusion, with AOMEI Partition Assistant, you can easily extend a partition under any of the situations that caused Extend Volume grayed out in Server 2019/2016/2012/2008/2003 or the latest Server 2022. Additionally, it provides many other useful features, such as convert to GPT/MBR disk without data loss, clone partition, clone Windows Server to SSD/HDD, quick partition, and so on.

If you want to install this program on the unlimited computer and manage your disk partitions conveniently, you can try AOMEI Partition Assistant Unlimited Edition.  The  Unlimited edition has a helpful function, Create Portable Version, enabling you to create AOMEI Partition Assistant to a removable device.