ERROR_DISK_CHANGE (0X0000006B) – Alternate disk not inserted error
This error means the program expected a specific disk and didn't find it. The fix is simple: reinsert the original disk or update the drive letter. I'll show you how.
This error is annoying but easy to fix
You're running an old program, and suddenly it stops with ERROR_DISK_CHANGE (0X0000006B). It means the program expected a specific disk (like a CD, DVD, floppy, or USB drive) and didn't find it. The culprit here is almost always a drive letter conflict or the wrong disk still in the drive.
The immediate fix
- Insert the original disk. If you have the original CD or floppy that the program came on, put it back in the drive. The program probably checks for that exact disk before continuing.
- If you don't have the disk, change the drive letter. Open Disk Management (
diskmgmt.msc). Right-click the drive with the missing disk (often D: or E:) and choose Change Drive Letter and Paths. Pick a letter that isn't used, like X:. Then mount the virtual disk or ISO file to that new letter. - Restart the program. It should now find the disk at the new drive letter.
Why this works: The program is hard-coded to look for a disk at a specific drive letter (usually D: or E:). If that letter is taken by another device (like a USB stick or card reader), the program throws ERROR_DISK_CHANGE. Changing the drive letter makes the disk appear where the program expects it.
Less common variations
Sometimes the error happens because the disk is dirty or scratched. Clean it with a soft cloth and try again. Also, old floppy disks can get demagnetized – no fix for that other than a backup image.
Another variation: if you're using a virtual drive (like with Daemon Tools or Alcohol 120%), the program might not see it as a real physical disk. In that case, mount the ISO directly in Windows (right-click > Mount) instead of using third-party software. That usually bypasses the issue.
On Windows 10 and 11, the error can also pop up when a USB drive is plugged in while the program is running. Unplug all USB drives except the one with the program disk. Then restart the program.
| Symptom | Probable cause | Fix |
|---|---|---|
| Error when inserting CD | Dirty disk or wrong label | Clean disk, verify label |
| Error after USB removal | Drive letter conflict | Change drive letter of USB |
| Error with virtual drive | Virtual drive not recognized | Mount ISO instead of using third-party |
| Error on startup | Floppy disk stuck or missing | Remove floppy, check BIOS settings |
How to prevent this
Three things to avoid this in the future:
- Keep the original disk handy. If you're running an old program, keep its CD or floppy in the drive while using it. Don't swap disks mid-session.
- Assign a fixed drive letter. In Disk Management, right-click the optical drive and set it to a letter that rarely conflicts, like R: (for ROM). That way USB devices won't steal it.
- Use a disk image. Rip the disk to an ISO file using something like ImgBurn (free). Mount the ISO in Windows directly – no need for the physical disk. Saves time and wear on the drive.
That's it. Most of the time, this error is just a drive letter squabble. Change the letter or put the right disk in, and you're good. No need to reinstall Windows or mess with drivers – skip that nonsense. It's almost never a hardware failure unless the drive itself is dead.
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