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Fixed: Disk Management Can't Extend Primary Boot Partition in Windows 10

Updated on Dec 05, 2018 by Tracy King to Partition Manager

When C drive gets full but you can't extend the primary boot partition with Disk Management, relax. This article explains why you can't extend C drive even with free space behind and provides a free method for you to extend primary partition in Windows 10/8/7 within 3 simple steps.

Disk Management can't extend primary C drive even with free space behind

"Yesterday, I was trying to increase my boot partition - C drive with more available free space on my PC. So I deleted the empty partition right behind C drive with Disk Management.

There, I got free space left right behind the boot partition - C: drive. Guess what? I was unable to extend my C drive even with free space. The 'Extend Volume' is greyed out in Disk Management. Yes, Disk Management can't extend boot C drive in my PC with free space left behind. I'm using Windows 10 by the way. Thanks for letting me know if you happen to just know something that can fix my problem."

According to Google searching result and multiple forums, it's not new that users fail to extend their primary partitions or boot partition (C drive) with Disk Management even with free space right behind. So what else can you do to add space to your system C drive? Here, this article will explain why you can't extend boot partition or increase primary space with Disk Management and provide an effective solution to help you complete the unfinished job with ease.

Why Disk Management can't extend primary C drive

To understand why the Disk Management can't extend primary C drive in Windows 10/8/7 or even earlier system, you'll need first to understand that how many primary partitions and extend partitions that you can have in Windows system on one disk.

Each disk can only have up to four primary partitions or three primary partitions and one extended partition. So here is the problem, at the very beginning, the primary partitions' space has been settled. And Windows system can't add free space or unallocated space from the extending partition to the primary partitions. 

And this is why even though you have free space in your PC, even right behind the primary partition, you may still fail to extend it. Unless you delete or shrink the primary partition right behind the target partition which you wish to extend. Any suggested solution? 

Solution: Extend primary/boot partition error with free partition manager freeware

So how to effectively extend boot partition and solve Disk Management can't extend primary partition error? Disk Management alternative free software will do. 

EaseUS Partition Master Free allows you to effectively add free unallocated space from extending partition to primary partition or boot C drive in Windows 10/8/7.

Download, install it on your PC and follow below step by step guide to get your primary partition extended now:

Download Now

 Windows 10 is supported

Extend primary partition C drive in Windows in 3 steps:

Step 1: Launch EaseUS Partition Master

Run EaseUS Partition Master

Step 2: Add space to the System C drive

1. Shrink partition and leave unallocated space for extending C: drive:

  1. Right-click on a partition next to the C: drive and select "Resize/Move".
  2. Drag the end of the partition that is next to the C: drive and shrink it, leaving unallocated space next to the system C: drive, and click "OK".

2. Right-click on the System C: drive and select "Resize/Move".

Extend System partition

To add space to the C: drive, drag the system partition end into the unallocated space.

Add space to C drive

Step 3: Confirm to extend system C drive

Click the "Execute Operation" button, it will list the pending operations, and click "Apply" to execute the changes and extend the C drive.

Confirm to extend system C drive

See, this is it. You've successfully fix Disk Management can't extend primary C drive partition error. If you can't increase partition, delete or create new partition with Disk Management, don't worry. EaseUS Partition Master will do.