The Symptom
When you try to shrink a volume with Disk Management, you may encounter the problem
that shrink volume not enough space. One situation is that it only shows a little
space that allows you to shrink when there is actually a lot of free space, the
other situation is that it shows enough space to shrink, but it gives an error that
there is not enough space available on the disk(s) to complete this operation while
trying to shrink a partition, in most of the case system partition.

The Cause
When other applications have made some changes to your partitions after you open Disk
Management, then the partition status shown in Disk Management is different from
what really is. Therefore, you will receive this error when you try to shrink
partition in Disk Management. Besides, when doing other operations that will make
changes to your partition status like Extend Volume, Delete Volume, you may also get
this not enough space available error message.
Additionally, you cannot shrink a volume with unmovable files located in the
middle of the partition. If there are page files or other unmovable/locked system
files at the end of the volume, it might also cause the problem there is not enough
space on the disk to complete shrinking volume.
Solution 1: Rescan Disks
In most of the cases, you can simply click the option “Rescan Disks” under “Action”
tab to fix this problem. After the partitions and volumes reloaded, you shall be
able to shrink volume or do other operations.
Solution 2: disable system files
To fix this Disk Management error not enough space, you need to disable the system
files as many as you can at this very moment. 1. Disable System Protection in
Control Panel\System and Security\System\System Protection.
2. Run Disk Defragment. Type in "disk defragmenter" in the search box, and
the defragment utility should show at the top of the search results.
3. Disable Hibernation mode by run the command “powercfg /hibernate off “in the
Command Prompt. In Windows 8/8.1 or Windows 10, the Hibernation mode is disabled as
default.
4. Disable the kernel memory dump. In the Advanced Settings, go to Settings under
Startup and Recovery, and then switch the drop-down menu under Write debugging
information to “None”.
5. Disable page files. In the same System, go to Advanced System Settings\Settings
under Performance\Advanced\Change, uncheck the option Automatically manage paging
file size for all drives, and check the option No Paging File. Restart your
computer, and then delete your c:\pagefile.sys file.
6. Run the Disk Cleanup. Open Disk Cleanup at the Properties of the partition you
want to clean up. Then click Clean up system files to remove the hibernation file
and all restore points.
After all these steps, you should be able to shrink volume the amount of
space you want. Unfortunately, if it still failed to shrink partition to a certain
amount of space, you can try a third party freeware.
Solution 3: use free partition manager program
AOMEI Partition Assistant Standard, a freeware works on Windows 10/8/8.1/7/XP/Vista,
is able to shrink a partition up to its total amount of free space.
To shrink partition with AOMEI Partition Assistant:
1. Download this free program. Install and launch
it.
2. Right click the partition or volume you want to shrink and select Resize Partition.

3. In the pop-out window, drag the slider leftwards or enter the new partition size
to shrink the partition. If you check the option I need to move this partition, it
allows you to shrink a partition from both sides.

4. Click Apply to run the operation.

Using this partition software, you won’t meet the problem that shrink volume not
enough space. If want to add the unallocated space to other partition, AOMEI
Partition Assistant allows you to add unallocated space to any partition on the same
disk by using the feature Merge Partition.
Besides, many useful functions are implemented in AOMEI Partition Assistant, such as
Migrate OS to SSD, Convert MBR to GPT disk
without data loss, Copy disk, and many more.