Windows server unable to extend the C driver even with free space on the disk

 Issue:

In my case i have 8GB of  space on my windows OS disk 0

But when i trued to extend the C driver from disk manager, the extend option is greyed out.

Solution:

1.Open "Command manager" (run->cmd)

2.Type "diskpart"

3.Type "list disk"

4.Type: "select disk 0" -> if your disk is different change the #

5.Type: "List partition"

6. Note down the "Recovery partition #" having size of ~500MB

7.Type "Select partition 3"

8.Type " delete partition override"

9.Tyep "select partition 2"  ->partition # from step3, our Cdriver partition

10.Type "extend"

Done