Fixed: External Hard Drive Unallocated Only on Windows 10

Learn how to fix the problem that external hard drive which works fine on Windows 7 and Windows 8 becomes unallocated only on Windows 10.


By Cherry / Updated on May 12, 2023

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Scenario: external hard drive unallocated only on Windows 10

A user from said: “My external hard drive works perfectly fine on my desktop (Windows 7), my laptop (Windows 8.1) but when I plug it into my brothers computer and my fathers (Both have windows 10) they say my drive is unallocated but it really isn't. My drive use to work on Windows 10 but it was after the very recent update (Like a few days ago) it has stopped loading my data on Windows 10 PCs. Any thoughts? ”

Actually, many users have this kind of problem such as external hard drive, USB drive, SD card or flash memory card that suddenly shows up as unallocated in PC. When you meet the problem, you need to know why it happens and how to fix the problem.

Why would external hard drive become unallocated on Windows 10?

There are many reasons would cause external hard drive suddenly becomes unallocated on Windows 10. and if you know the exact reasons, you can solve the problem easily.

1. You can open Windows Disk Management to see whether the external hard drive existing, if it is shown as unallocated space, you need to consider whether its drive letter has changed.

2. File system error is another cause for external hard drive suddenly becomes unallocated.

3. The external hard drive internal error. If the external hard drive has physical damaged problem, it may shows unallocated space on PC.

4. An improper operation such as unplugging drive improperly from PC may also cause the external hard drive shows unallocated space in Windows.

5. Virus attack.

6. Hard drive driver is outdated. If the hard drive driver is outdated, it may be shown as unallocated space in Windows Disk Management.

How to fix drive unallocated space on Windows 10?

As there are different reasons for external hard drive unallocated only on Windows 10, here we provides you different methods to fix drive unallocated space on Windows 10.

1. Free download some anti-virus software to check whether it is because of virus attack. If it is, you can move the virus in your PC and the external hard drive.

2. Update hard drive driver. If you find your hard drive works fine on Windows 7 and Windows 8 while becomes unallocated only on Windows 10, you should check whether your hard drive driver is outdated.

>Click Start button, type Device Manager, select it from the list of results.

>You may see your external hard drive here with a yellow alert. Right click the hard drive, select Update Driver.

>Select Search automatically for updated driver software.


If Windows doesn’t find a new driver, you can try looking for one on the device manufacturer’s website and follow their instructions.

If these steps don’t work, try reinstalling the driver. Open Device Manager, right click the name of the device, and select Uninstall. Restart PC and Windows will attempt to reinstall the driver.

3. Run CHKDSK to check and fix the external hard drive.

Press Win+R, type cmd and run the progress as administrator.

Type chkdsk f: /f /r /x.

Chkdsk f f r x


f: refers the drive letter of the drive that you need to check.

/f will fix the errors found in the drive.

/r will locate the bad sectors on the drive and recover readable information.

/x forces the drive to dismount before the process starts.

4. If there is no problem with external hard drive, you should consider whether it is because of the file system error. If so, you need to recreate a partition on the unallocated external hard drive so that it can be reusable again.

* If you do not want to lose data, you can restore data from unallocated external hard drive with some data recovery software like iCare Data Recovery, which can help you scan the disk and get all data you need before formatting.

After restore data from the unallocated external hard drive, you can fix and repair external hard drive unallocated on Windows 10/8/7 by recreating a partition on the unallocated external hard drive. To fix and repair unallocated external hard drive, here we highly recommend you the free partition manager AOMEI Partition Assistant.

Step 1. Free Download AOMEI Partition Assistant. Install and launch it to your Windows 10/8/7. it will show you its main interface. Click the unallocated disk, select Test > Disk Surface Test.

Surface Test

Step 2. It will help you to check whether there is bad sectors on the hard drive.

Start Surface Test

Besides, you can use Check Partition to check and fix errors on the hard drive.

After checking and fixing errors on hard dive, you can use AOMEI Partition Assistant to create partition on the hard drive with three steps.

Step 1. Right-click the unallocated space, and select Create Partition on the pop-up menu.

Create Paqrtition

Step 2. Here you can set up the details for the new partition, like specify the partition size, assign a drive letter, choose File System, and more advanced options. After settings, click OK.

Create Partition Detail

Step 3. Here, confirm the pending operations, and click Apply to submit all operations.


As so far, you have already solved the problem that external hard drive unallocated only on Windows 10.

AOMEI Partition Assistant Standard should be the best free partition manager for Windows 10/8/7 users. You can use it to solve the most partition problems. Besides, you can upgrade to AOMEI Partition Assistant Professional edition to unlock more advanced features like allocate free space, dynamic disk converter, partition alignment, etc.

Cherry · Staff Editor
Cherry is an editor of AOMEI Technology, she covers backup & restore, hard disk & partitions management, cloud files transfer, website & database backup and so on for AOMEI. She enjoys helping people find solutions to their problems. She loves traveling, cooking, reading and so on. She takes most of time with her family when she is not working.