Drive Letter Not Available: Everything You Should Know

Updated by Cici on Jan 16, 2023
  | Computer Instruction

When you see the message "drive letter not available" while trying to access a storage device on your computer, it can be frustrating and confusing. This error can happen for many reasons, making it hard to get to important files or use your device normally.

But fear not! There are steps you can take to troubleshoot and potentially fix the problem. This article will explore everything you should know about this error, including its causes, how to troubleshoot it, and potential solutions to get your device back in working order.

Why Is the Drive Letter Not Available

A "drive letter" is assigned to a drive or partition in a computer's file system. It enables the operating system to identify and access the drive or partition to read and write data.

The "drive letter not available" error indicates that the operating system does not recognize the drive or partition you are attempting to access. There are several reasons why the "drive letter not available" error can occur:

1. The drive letter has been permanently assigned to another drive or partition

A drive letter is a unique identifier for each partition or drives on a computer. If you have permanently assigned a drive letter to another drive or partition, including the CD/DVD, you might not be able to use it on the drive or partition you are trying to access. This can lead to the error "drive letter not available."

2. The drive letter is occupied by a hidden removable device

The "drive letter not available" error could also be caused by a hidden removable device, like an external hard drive or USB drive, using the drive letter.

These devices are typically assigned a drive letter when connected to the computer, but the drive letter may still be reserved for them if they are not connected. This can cause the "drive letter not available" error to appear when you try to access the drive or partition.

How to Fix Drive Letter Not Available

Now that we've discussed some things that could cause the "drive letter not available" error let's discuss how to fix it. To fix this issue, you'll need to go through a two-phase process: releasing the unavailable drive letter and then assigning it again:

Guide 1: Release the Unavailable Drive Letter

Guide 2: Assign the Available Drive Letter

The first phase will allow you to make it available on the drive or partition you are trying to access. While the second step will let the operating system recognize and access the drive or partition, so you can read and write data to it as usual.

To fix the "drive letter not available" error, we've written detailed instructions on releasing and reassigning drive letters.

Guide 1: Release the Unavailable Drive Letter

You'll need to use the Registry Editor to release the unavailable drive letter. The Windows Registry is a strong instrument tool that lets you see and change how your computer's operating system is set up and configured. It is a useful tool for troubleshooting and fixing different problems, like the "drive letter not available" error. Here's how to use it:

Step 1.  Enter "regedit" into the Start menu to launch the Registry Editor. 

Step 2.  In the Registry Editor, navigate to the following key:

HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices

release drive letter 1

Step 3.  In the MountedDevices key, look for the drive letter causing the "drive letter not available" error. You'll see a list of entries with names like "D," "E," etc. 

Step 4.  Right-click on the drive letter and select "Export." This will create a backup of the key if you ever need to restore it. It's important to create a backup before making any changes to the Registry, as incorrect changes can cause serious problems with your system.

release driver letter 2

Step 5.  After creating the backup, delete the drive letter key. This will release the drive letter and make it available for use.

Step 6. Close the Registry Editor and restart your computer. This is necessary to apply the changes you made to the Registry.

After the restart, the drive letter should now be available for use. You can now move on to the next phase of the process, which is reassigning the drive letter.

Notice:
It's essential to be careful when editing the registry, as incorrect changes can cause serious problems with your system. Follow the instructions precisely, and before making any changes, always make a backup with professional backup software.

Guide 2: Assign the Available Drive Letter

To assign the available drive letter, you'll need to use EaseUS Partition Master. EaseUS Partition Master is a partition management tool that allows users to create, delete, resize, and move partitions on their hard drives. One of the useful features of EaseUS Partition Master is its "Change Drive Letter" function, which allows users to change the drive letter of a partition easily.

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To use the "Change Drive Letter" function in EaseUS Partition Master, follow these steps:

Step 1. Run EaseUS Partition Master, right-click the target partition, and choose "Change Drive Letter".

Step 2. In the new window, click the down arrow and choose a drive letter for the partition from the drop-down menu, then click "OK".

Step 3. Click the "Execute 1 Task(s)" button in the top-left corner, check the changes, and click "Apply" to change the drive letter of the selected partition.

After you follow these steps, the partition should now have a drive letter so that you can use it as usual.

EaseUS Partition Master is a wonderful tool to replace Windows built-in tools to fix change drive letter greyed out in Windows. This powerful tool also offers a lot of functions related to disk partition. Some of the features and functions offered by EaseUS software include:

As a comprehensive disk partition tool, it can not only provide you with more new functions but can also fix the old problems in your computer and improve its performance. 

Step 1. Run EaseUS Partition Master, right-click the target partition, and choose "Change Drive Letter".

Step 2. In the new window, click the down arrow and choose a drive letter for the partition from the drop-down menu, then click "OK".

Step 3. Click the "Execute 1 Task(s)" button in the top-left corner, check the changes, and click "Apply" to change the drive letter of the selected partition.

Conclusion

Having the "drive letter not available" error pop-up is extremely annoying because it prevents you from opening files or using your device normally. To fix this, release the unavailable drive letter and assign it again.

The Registry Editor can delete the error-causing drive letter key to free up the unavailable drive letter. You can use EaseUS Partition Master, which has a proper "Change Drive Letter" function that makes it easy to change the drive letter of a partition and assign the available drive letter. We recommend downloading EaseUS Partition Master to fix the "drive letter not available" error and restore access to your drive or partition.

FAQs About Drive Letter Not Available

If you have further questions about the "drive letter not available" error, you'll find their answers. We've compiled a list of common questions and provided detailed answers to help you resolve this issue and regain access to your drive or partition.

1. Why is my drive letter not available?

It may be due to the following:

  • The drive letter is permanently assigned to another partition.
  • A hidden removable device, such as an external hard drive or USB drive, occupy it.
  • Drive partition or file system issues.
  • Drive hardware failure or corruption.
  • The operating system or hardware is broken.

2. How do I make a drive letter available?

To make a drive letter available, you'll need to follow these steps:

Step 1. Enter "regedit" into the Start menu to launch the Registry Editor.

Step 2. In the Registry Editor, navigate to the following key: HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices.

Step 3. Right-click on the drive letter and select "Export."

Step 4. After creating the backup, delete the drive letter key.

3. Why can't I assign the drive letter D?

You might not be able to assign drive letter D for several reasons:

  • Another drive or partition already uses the drive letter D on your computer.
  • The drive letter D is reserved for a hidden removable device, such as an external hard drive or USB drive.

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