Fix ERROR_NO_MORE_DEVICES (0x000004E0) on Windows

Quick answer

Open Disk Management (diskmgmt.msc), right-click the drive showing the error, and choose Change Drive Letter and Paths. Remove an unused letter from another drive (like a DVD drive at Z:) or mount this drive to an empty NTFS folder instead.

Why you're seeing this

Windows only supports drive letters A through Z. That's 26 letters, minus A and B reserved for floppy drives (though modern systems don't enforce that anymore). So you've got 24 usable letters. If you've got a lot of USB drives, network drives, or old recovery partitions that grabbed letters, you'll hit the wall.

This error usually pops up when you plug in a new external drive, insert an SD card, or attach a new internal disk. Windows tries to assign the next available letter, finds nothing left, and throws 0x000004E0. I've seen this most often with users who map multiple network drives and keep USB flash drives plugged in all the time.

Fix it: Free a drive letter

1. Press Win + X and select Disk Management. Or just type diskmgmt.msc in the Run box (Win + R).
2. Look at the list of volumes. You'll see each one with a drive letter. Notice anything assigned to Z: or Y: that doesn't need to be? Common culprits: DVD drives, memory card readers, recovery partitions that somehow got letters.
3. Right-click the volume you want to free up (say your DVD drive at Z:) and choose Change Drive Letter and Paths.
4. Click Remove. Yes, it'll warn you that programs using that path might break. That's fine—nothing critical uses the DVD drive letter these days.
5. Now right-click the drive that had the error and assign the freed letter. Or let Windows pick the next available one.

That's it. If you removed a letter from Z:, you'll have Y: and Z: free for future drives.

Alternative: Mount to a folder

Don't want to play musical chairs with letters? Mount the drive to an NTFS folder. This is cleaner for drives you keep plugged in. Here's how:

1. In Disk Management, right-click the problem drive and choose Change Drive Letter and Paths.
2. Click Add.
3. Select Mount in the following empty NTFS folder, then browse to an empty folder on any NTFS drive (like C:\ExternalDrive). Create the folder first if needed.
4. Click OK. The drive will appear as a folder in File Explorer, not as a separate letter.

This bypasses the letter limit entirely. I mount all my external SSDs this way—keeps the system tray uncluttered and avoids conflicts.

Other things to check

• Network drives: Open File Explorer, right-click any mapped network drive, and select Disconnect if it's not needed. Each mapped drive eats a letter.
• Hidden USB drives: Some flash drives or card readers show up with letters even when nothing is inserted. You can remove those too.
• Registry hack: You can technically assign letters A or B to disks, but Windows doesn't recommend it. If you're desperate, go to HKEY_LOCAL_MACHINE\SYSTEM\MountedDevices in regedit and rename entries. I'd skip that—too easy to mess up your boot drive.

Prevention tip

Stop mapping network drives to letters you don't need. Use UNC paths (like \server\share) instead. And clean up leftover USB drives in Disk Management after you unplug them—they sometimes hold onto letters even when disconnected. I do this once a month and haven't hit the 24-letter limit since.