There are a few common reasons why you may be unable to format your USB drive:
Corrupted File System
One of the most common causes of being unable to format a USB drive is a corrupted file system. The file system manages how data is stored on the drive. If it becomes corrupted, which can happen from improper ejection, viruses, or physical damage, then the drive may become unreadable by your computer.
When attempting to format a USB with a corrupted file system, you may get errors like “USB Drive is not accessible” or “Windows was unable to complete the format”. The drive may show up in your computer’s file explorer but be unusable or missing data. Formatting can fail because the necessary file system structures are damaged.
How to Fix a Corrupted File System
There are a few options to try to fix corruption and reformat the USB drive:
- Use Windows built-in error checking and disk repair tools. Right click the drive, go to Properties > Tools > Check. Checkdisk can find and repair basic errors.
- Use third party disk repair software that may provide more extensive repair capabilities for corrupted drives.
- Low level format the drive to completely reset the file system. This will erase all data though.
Drive Became Read-Only
Another potential cause for being unable to format a USB drive is if the drive has somehow been set to read-only mode. With a read-only state, the drive will be locked and protected against any changes, including formatting.
Drives can sometimes have the read-only attribute enabled accidentally or by hardware damage and controller issues. When trying to format, Windows will alert that the drive cannot be formatted while read-only.
How to Make a USB Drive Writable Again
A couple steps to make a read-only USB drive writable again include:
- Use diskpart utility in Windows to remove the read-only attribute. Open diskpart, select the USB drive, then issue ‘attributes disk clear readonly’ command.
- Try using disk management instead to clear the readonly state by right clicking the drive and unchecking Read-only in the properties.
- If set read-only by hardware damage, you may need drive repairs instead to fully reset the read-only status.
Drive is Physically Damaged
Physical damage to the USB drive can also prevent properly formatting the disk. Issues like bad sectors, failed read/write heads, and corrupted flash memory cells can interfere with low level formatting.
Signs of a physically defective USB drive include the format failing immediately or very quickly, drive making unusual noises during access, and other consistent read/write errors. The USB itself may also show signs of damage like cracks or bends.
Repairing Physically Damaged USB Drives
Options for troubleshooting physical USB drive damage include:
- Use manufacturer tools to test for and repair detected hardware issues.
- Low level format tools may mark bad sectors as unusable and prevent further issues.
- Try formatting on a different system to ensure issue is with the drive and not your computer.
- In severe cases, the USB may need professional data recovery to attempt fixing it.
- Otherwise, the USB likely needs replacement if physical damage is the root cause.
Insufficient Permissions to Format Drive
Permission errors can also lead to being unable to format a USB drive on your system. By default, only Administrators have the authorization to format drives on a Windows computer. Standard or guest user accounts may run into permission issues.
When trying to format as a limited user, you may see errors like “Access denied” or “You need administrative rights to format this drive”. The format process starts but quickly fails due to the lower permissions.
Granting Permissions to Format USB Drive
To grant permissions for other users to format, you can:
- Log into an Admin account that has full permissions to format the USB drive.
- Provide standard users administrative rights temporarily with the Run As Administrator option.
- Change NTFS permissions on the USB drive to allow Write access for other users trying to format.
USB Drive Already Mounted and In Use
If a USB drive is currently mounted and files are in use, the reformatting process can be blocked. The format involves rewriting low level structures, which requires full exclusive access.
Errors that indicate the USB is already busy include “The volume is in use by another process. Formatting may cause data loss.” Attempting to format will fail right away in this case.
Unmounting an In Use USB Drive
Before a mounted USB drive can be formatted, any running programs need to close their open files and the drive properly ejected:
- Close all Explorer windows and applications using files on the USB drive.
- Use Safely Remove Hardware icon in system tray to eject the USB drive.
- Confirm the USB drive is no longer showing in Explorer or Disk Management as mounted.
- Now the USB should format without errors about the drive being in use.
AutoPlay Set as Read-Only
Windows includes an AutoPlay feature that can mount USB drives as read-only automatically. This prevents formatting from taking place until changed.
You may notice the drive already shows as read-only when first inserted. Trying to format results in “Cannot format this drive. Quit other programs and try again or format it in Safe Mode.”
Disabling AutoPlay Read-Only
To allow formatting drives that AutoPlay mounts read-only, you can either:
- Disable AutoPlay completely in Control Panel > Hardware and Sound > AutoPlay.
- OR change the default AutoPlay setting from Read-Only to Take No Action.
Now when you insert the USB drive, AutoPlay will not interfere with formatting it.
Drive Locked by Encryption
If a USB drive is encrypted by BitLocker or a similar program, the encryption will prevent formatting the actual drive.
When trying to format an encrypted drive, Windows will display errors like “There was a problem resetting this drive: Access denied. Encrypted Drive. Use BitLocker to turn off encryption.”
Bypassing Encryption to Format
To reformat an encrypted USB drive, you need access to either the encryption password or recovery key to first unlock the drive.
- Use BitLocker recovery tools to unlock encrypted drive by providing the passkey.
- Turn off BitLocker encryption from Drive Properties > BitLocker > Turn off BitLocker.
- With encryption disabled, the USB drive will now format normally.
Conclusion
In summary, being unable to properly format a USB drive is often caused by file system corruption, physical damage, drive permissions, being mounted already, AutoPlay settings, or drive encryption.
To troubleshoot and fix, first determine the exact error when trying to format. Then apply the appropriate solutions like using disk checking tools, unmounting the USB drive properly, disabling read-only states, replacing severely damaged drives, granting administrator access, turning off AutoPlay, or decrypting the drive before formatting.
Following the troubleshooting steps for your specific issue should resolve most cases where a USB drive cannot be formatted. The drive should format successfully after identifying and correcting the underlying problem preventing the format.
| Error Message | Potential Cause | Solution |
|---|---|---|
| USB Drive is not accessible | Corrupted file system | Use Check Disk or low level format tools to fix file system errors |
| Windows was unable to complete the format | Damaged USB drive | Check drive for physical damage. Use drive repair tools. |
| Access denied | Insufficient permissions | Run as Admin or change NTFS permissions to allow Write access |
| The volume is in use by another process | USB drive already mounted | Eject drive properly in Safe Remove Hardware before formatting |
| Cannot format drive while Read-Only | Read-only attribute enabled | Use diskpart or disk management to remove read-only state |
| Cannot format – Encrypted Drive | USB drive encrypted | Turn off BitLocker encryption before formatting drive |
Formatting a USB drive is an essential maintenance task to reset the drive, remove viruses, and address performance issues. Understanding potential reasons formatting can fail allows you to get USB drives back up and running again.
If the solutions outlined do not resolve your specific USB formatting issue, contact the drive manufacturer for further support troubleshooting why the format fails and how to get your drive back to a usable state.
