Why Can't I Extend the System Partition in Windows 10 Even When I Have Unallocated Space?

I have done a little research about how to extend my system partition with Disk Management of Windows. And I have enough unallocated space at the end of my hard drive. Why can't I extend the system partition in Windows 10 even when I have unallocated space? What can I do with this problem?

According to your description, you failed to extend partition C with Disk Management when you have unallocated space on the drive. Before we walk through the solution, let's view two common reasons why you are unable to extend the system partition in Windows 10, even when you have unallocated space:

• The unallocated space is not adjacent to partition C. To extend a partition, the unallocated space must be behind the partition you want to extend.
• Another process or application locks the system partition, so you can not resize the partition.

It's exhausting to check and solve these problems, so you can try to use a professional partition manager - EaseUS Partition Master. It's an easy-to-use and full-featured software that can offer multiple methods to extend C drive in Windows 10 without effort. According to how much partition C space is consumed, you can apply the "Adjust with 1-Click" and "Resize/Move" tools of EaseUS Partition Master.

Now, you will learn the comprehensive instructions as follows:

Situation 1. System Partition Is Full

If the C drive is out of space and has a low disk space warning message, you can use "Adjust with 1-Click" to add more space on the system partition with one click:

Situation 2. System Partition Is Almost Full

If the C drive runs out of space and will get full soon, "Resize/Move" may suit your situation better.