The installer is open, but your pendrive is not listed, not accepted — or worse, several drives are showing and you are not sure which one is safe to pick. Detection problems and wrong-drive fear both get solved here, before any formatting happens.
✍️ Technical Anshu🪟 Windows 10 / 11⏱️ 7 minute read
🎥 Watch how the drive letter is confirmed in the video before installing
The MediCat installer works with the drive you point it to, so the drive must be visible to Windows and you must know its exact letter. If the installer seems to ignore your USB, the cause is usually the port, a hub, a half-dead pendrive, or a drive Windows itself has not mounted properly. And if you can see too many drives — that is a safety problem, solved by one simple habit.
Disk ManagementStatus
Disk 0 — Basic — 465.76 GB — Online
Windows (C:)Healthy (Boot, Page File)
Disk 1 — Removable — 58.43 GB — Online
(No drive letter)Unallocated
A pendrive that Windows can see in Disk Management but has no drive letter — the installer works with letters, so this drive is invisible to it until a letter is assigned (Fix 2).
1
Plug Directly into the PC — Skip Hubs and Front Panels
USB hubs, keyboard ports and cheap front-panel sockets are the most common reason a drive "disappears" during a long format-and-copy job:
Remove the pendrive and plug it into a USB port directly on the motherboard — on a desktop, that means a rear port; on a laptop, a port on the body itself.
Wait 10 seconds and check File Explorer: the drive should appear with a letter, for example E: or F:.
If it appears and disappears repeatedly in any port, the pendrive itself is failing. Test it on another PC if you can — a dying drive will also fail halfway through the install, so replace it now rather than later.
2
Check the Drive in Disk Management
If File Explorer shows nothing, Windows may still see the hardware. Disk Management shows the truth:
Press Windows + R, type diskmgmt.msc and press Enter.
Look for your drive in the lower list by its size (for example, a 64 GB pendrive shows as roughly 58-59 GB — that difference is normal).
If the drive appears without a letter, right-click its main partition → Change Drive Letter and Paths → assign any free letter. The installer needs a letter to work with.
If it shows as RAW or Unallocated, do not worry for this job: the installer formats the drive anyway. Just be certain it is the pendrive and not another disk.
If the drive does not appear here at all, Windows truly cannot see it — try another port, another PC, and then accept the drive may be dead.
3
Disconnect Every Other External Drive (Safety Step)
If your worry is the opposite — too many drives — this is the fix technicians use:
Unplug all external hard disks, other pendrives, memory card readers and phone storage before starting the installer.
Leave only the target pendrive connected. Now the drive letter you noted in File Explorer can only belong to it.
Double-check the letter one last time in File Explorer right before typing it into the installer. Letters can change when devices are plugged and unplugged.
The installer will erase the drive behind the letter you type. This 20-second habit is the entire defence against wiping the wrong disk.
This PC — Devices and drives
💽 Local Disk (C:)System drive
💽 Backup Drive (D:)External HDD
🔌 USB Drive (E:)Pendrive?
🔌 USB Drive (F:)Or this one?
Too many similar drives is exactly how the wrong disk gets wiped. The safety habit from Fix 3: disconnect everything except the one target pendrive.
4
Re-run the Installer as Administrator, After Connecting the Drive
Order matters more than people expect:
Connect the pendrive first and confirm its letter in File Explorer.
Only then start the installer, with a right-click → Run as administrator. Without admin rights, the script may not be able to access or format removable drives on some systems.
If you plugged the drive in after the installer was already open and it still is not accepted, close the installer completely and reopen it — it checks drives when it starts, not continuously.
Still stuck? Try the second known-good USB port on the machine and a freshly extracted copy of the installer, then compare with the video above, which shows the drive being selected and accepted.
🔴 Hard rule: if you cannot positively identify which letter is your pendrive, stop. Do not "try one and see" — the installer formats first and asks nothing later. Identify it by size in Disk Management, or disconnect everything else.
🎥 Watch the Complete Process in the Video
The video shows the drive letter being checked and the installer accepting the drive — match your screen to it.
My pendrive shows 58 GB instead of 64 GB. Is it fake?
No — that difference is normal. Manufacturers count capacity in decimal (64 GB), Windows counts in binary, so a genuine 64 GB drive displays around 58-59 GB in Windows. A much larger shortfall (for example 64 GB showing as 8 GB) is a real problem.
Can I use an external hard disk or SSD instead of a pendrive?
Yes. MediCat works on external HDDs and SSDs too, and a portable SSD is actually faster and roomier. The same warning applies with more force: the installer erases the whole selected drive, so never point it at a disk holding your backups.
The installer formatted the drive but it vanished from Explorer. Broken?
Usually not. During installation the drive's partitions are being rebuilt by Ventoy, and Windows may not show a letter until the process finishes. Let the installer complete, then unplug and reinsert the drive — it should reappear, ready to boot.
This guide is based on the Technical Anshu MediCat USB video • Stuck on any step? Ask in the video comments — help is available there 🙏