The issue happens because the KeyArmor was formatted with FAT 32 that limits the size of the file transfer to 500MB. To resolve the issue, you need to format the drive from FAT32 to NTFS:
- Right-click My Computer (Windows XP) or Computer (Windows Vista and 7) and select Manage.
- Open the Device Manager and find your USB drive under the Disk Drives heading.
- Right-click the drive and select Properties.
- Go to Policies tab and select the Optimize for performance option.
- Click OK.
- Open My Computer or Computer.
- Select Format on the flash drive.
- Select NTFS in the File System drop-down box.
- Click Start and wait until the process is completed.
Note: To remove a device safely without data loss, use Safely remove hardware procedure or Eject function.