USB drive won't format

Symptoms

• Format fails with an error partway through or immediately
• 'Windows was unable to complete the format' message
• Drive shows as write-protected when trying to format
• Format works using one tool but not another

Likely causes

• CommonWrite protection enabled, either physically or in softwareA locked drive can't be formatted until protection is removed.
• PossibleBad sectors preventing the format process from completingPhysical damage can make certain areas of the drive unwritable.
• PossibleFailing or worn-out flash memory controllerCheap or heavily used flash drives can degrade to the point of being unformattable.
• PossibleFile system requested is incompatible with the drive's current stateTrying to format a very large drive as FAT32, for instance, can fail due to size limits.

What to do

1. Check for a physical lock switch on the drive and make sure it's unlocked.
2. Run 'diskpart', select the disk, and try 'attributes disk clear readonly' to remove software write protection.
3. Try formatting through Disk Management, and if that fails, try the command line with 'format' specifying a different file system.
4. Try a different, smaller file system like exFAT or NTFS if a large FAT32 format is failing due to size limits.
5. Use a manufacturer-specific low-level format tool if the drive brand provides one.
6. If all format attempts fail with errors, the drive's memory controller has likely failed and it should be replaced.

Safety