Problem solved: faulty primary partition without drive letter in windows 11/10/8/7

Have some problems about primary partition without drive letter in Windows 7/8/10/11? This guide shows you the details guide to fix easily and safely.

by Hannah / Last updated 18.10.2021

About error free primary partition

What does error free primary partition mean? The error-free primary partition is a partition that contains Windows system/boot files(io.sys, bootmgr, ntldr, etc.), system recovery files, or other data. It is the only partition that can be set as active. Normally Windows provides one or more primary partitions. On one MBR disk can be maximum 4 primary partitions or 3 primary partitions plus 1 extended partition. For GPT disks there are all primary partitions.

An error-free primary partition can be an EFI system partition, a recovery partition or an active primary partition of the system (usually the C: drive) etc. be. In one word the error free primary partition without drive letters the typical EFI system partition or recovery partition etc. show. Also, an error-free primary partition that is no longer accessible(the primary partition has no drive letter) may have a problem in Windows Explorer for some reasons. We analyze the following two cases.

2 cases:

Case 1: I have a Windows 7 computer that shows these partitions:
1. Error free, active, recovery partition. 1.46GB.
2. C: Error free, boot partition, swap file, crash image, primary partition. 451.3 GB.
3. Primary partition 13 GB.
All these partitions are on disc 0. It is the third partition without a drive letter that I am asking about, about that I have. Can I add the third partition to the C: drive. This computer is factory partitioned. I have no idea about the third partition and how to figure it out? Any help would be appreciated!

Case 2: Hi, I have question that my faulty primary partition on a GPT disk in Disk Management somehow has no drive letter. So the error-free primary partition is no longer accessible in Windows Explorer. Now I want to assign a drive letter to the error-free primary partition to display it. However, I find that the option "Change drive letters and paths" is grayed out, only the option to delete the volume is available. What do I have to do to show the primary partition with errors??

Change drive letter grayed out

Complete solutions for case 1: Faulty primary partition without drive letter

In case 1 you can delete the error free primary partition to get more free space if you make sure that these files are no longer needed. It is strongly recommended to back up primary partition to avoid data loss. There are two ways to manage the active primary partition of the system without drive letters: Disk Management and the best Windows partition software.

Disk management

– Select "This PC" on the desktop -> "Manage" off to open the "Computer Management" to open.

– Select "Disk Management under "Data Storage from.

– Right click on the faulty primary partition and select "Delete volume", to get an unallocated space.

Delete Volume

– Now you can merge unallocated space with C: drive to extend the system partition in Disk Management.

Extend volume

What you should know about Disk Management can extend a partition only with adjacent unallocated space. You must not extend the partition if the unallocated space is not behind it. You may try another reliable method to fix an error-free active primary partition without drive letters.

The best partitioning software – AOMEI Partition Assistant Pro

With this all-in-1 partition software, you can manage your hard drive, SD card, USB flash drive and other memory sticks. You can perform splitting, merging, formatting, deleting, moving partitions, assigning drive letters, etc. perform.

This comprehensive hard disk partitioning software is easy to use as disk management due to advanced features and user-friendly interface; you could merge the C: drive and the error-free primary partition without drive letter with simple clicks. You don’t need to delete the bad primary partition at first. To merge the healthy primary partition and the system partition (C: drive) in Windows 7/8/10/11.

I. Download, install and run this partitioning utility. Right-click on the C: drive or the bad primary partition without a drive letter, and then select Merge partitions.

Merge Partitions

II. Check both drive C: and the corrupted primary partition, and then click on OK.

Select partitions

III. Finally click Execute, to extend C: drive.

Apply Merge

Solutions for case 2: Faulty primary partition has no drive letter

In case 2, the clean primary partition without a drive letter is not displayed in the explorer, and the "Change drive letters and paths" option is grayed out in Disk Management. Why your computer refuses to assign a drive letter to the bad primary partition? Here are some reasons:

– The volume is not formatted with FAT or NTFS. If you connect the drive from a Mac computer, it means that the volume is formatted with Apple File System (APFS) and is not compatible with Windows operating system. you need to format it to FAT or NTFS.

– The drive is write-protected. If the hard disk drive is write-protected, you cannot assign a drive letter in Windows. Therefore, you must first remove the write-protection from the hard disk and then assign the drive letter.

After formatting to FAT/NTFS or removing write protection, switch to Disk Management and assign a drive letter to it. Browse your files on this faulty primary partition.

Besides, you can also use AOMEI Partition Assistant Pro to assign a drive letter to the drive. Here are the steps:

1. Run AOMEI Partition Assistant after right-clicking on the primary partition with the error, select "Advanced"> "Change drive letter".

Change drive letters

2. Select a drive letter for the primary partition in error and click "OK".

New drive letter

3. Finally, click "Run" to solve the "corrupted primary partition without drive letters" problem.

Change drive letter

In addition, you can use the program to format or delete the bad primary partition according to your needs.


With the help of the best partitioning software you have successfully solved the problem. You can also use the software to allocate free space, split partition, convert primary partition to logical one, migrate operating system to SSD or HDD. Server Edition includes all Advanced Features of Professional Edition, and supports Windows Server 2003, 2008 (R2), 2012 (R2), 2016, 2019, 2022 and SBS 2003, 2008, 2011.

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