Do these 3 things before closing this tab:
1Repair Windows errors before they cause bigger problems2Fix the driver behind crashes, sound loss and screen glitches3Clear out junk files and repair common Windows errorsThe Windows message “The system cannot find the device specified” is Win32 error ERROR_BAD_UNIT, hexadecimal 0x00000014 (decimal 20). It is a generic device-layer error, not a diagnosis of one particular component. Work through connection checks first, then identify how Windows sees the device, update or reinstall its driver, and only then use storage or system-repair procedures. If the device is missing on several ports and computers, or read, write, or CRC faults appear, treat the cable, enclosure, power supply, or device itself as the likely failure.
What error 20 means
Microsoft’s Win32 reference maps ERROR_BAD_UNIT to 0x00000014 (decimal 20) and gives the exact text: The system cannot find the device specified.
The wording describes what Windows could not locate at the moment an operation was attempted. It does not tell you whether the cause is a USB connection, a missing driver, a disk with no mounted volume, a printer or scanner, a network adapter, or damaged system software.
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Do not confuse error 20 with nearby device conditions in Microsoft’s table. “Device not ready,” a CRC or data error, a read fault, a write fault, and a general attached-device failure are separate statuses and require different decisions. Record the exact message and any second code shown by the application or Event Viewer before changing anything.
First identify where the failure occurs
The same message can be raised by Windows itself or by one application. Start by noting the action that fails: opening a drive, copying a file, printing, scanning, connecting to a network, launching a game, or using a USB accessory. Then check each Windows view below.
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| What you observe | Most useful next branch |
|---|---|
| The item appears in Device Manager | Inspect its status and driver; update, reinstall, or roll back the driver. |
| A disk appears in Disk Management but not File Explorer | Check whether it is initialized, online, partitioned, and assigned a drive letter. |
| The item appears nowhere in Windows | Test the port, cable, power, and another computer before software repair. |
| Only one application reports the message | Check that application’s selected device, permissions, plug-ins, and local configuration after confirming Windows detection. |
This distinction prevents a storage-only remedy, such as assigning a drive letter, from being applied to a printer, USB controller, audio device, or network adapter.
Safe checks before changing drivers
Restart and reconnect
- Save work and restart Windows. A restart clears a device state left by a failed sleep, update, or application.
- After signing in, unplug the device, wait several seconds, and reconnect it directly to the computer.
- Try a different USB port. On a desktop, test both a rear motherboard port and a front-panel port; on a laptop, test ports on opposite sides when available.
- If the device has a detachable cable, test a known-good cable of the correct type. For a hard drive or other high-power device, connect its supplied power adapter and avoid an unpowered hub during testing.
- If possible, connect the device to another computer. A failure that follows the device points toward its cable, enclosure, power, or hardware; a failure limited to one PC points toward that PC’s port, driver, or Windows installation.
Install pending Windows updates
Open Settings > Windows Update (in Windows 11 and Windows 10), select Check for updates, install applicable updates, and restart when requested. Updates can include device drivers and the USB, storage, networking, or printing components that communicate with the hardware. Test again before moving to more invasive changes.
Check Device Manager
Device Manager is the correct place to investigate a peripheral, printer, scanner, network adapter, graphics card, audio device, Bluetooth device, USB controller, or other component that Windows recognizes at some level.
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- Right-click Start and select Device Manager.
- Expand the category that matches the hardware. For removable storage, inspect Disk drives and Universal Serial Bus controllers; for networking, inspect Network adapters; for printers and scanners, inspect the relevant imaging or printer entries.
- Look for a yellow warning icon, an unknown device, or an entry that disappears when you unplug the hardware.
- Right-click the device, choose Properties, and read the Device status text on the General tab. Record any additional code before proceeding.
Update automatically
- In Device Manager, right-click the affected device and select Update driver.
- Choose Search automatically for drivers. Windows may search locally and through Windows Update.
- Restart if Windows installs a driver, then repeat the operation that produced error 20.
Microsoft notes that Windows Update normally supplies drivers for hardware such as network adapters, printers, scanners, and video cards. Automatic search may report that the best driver is already installed even when the manufacturer has a newer package, so continue to the manual method if the problem began after a driver change or remains unresolved.
Install the manufacturer’s driver manually
- Identify the exact model and revision printed on the device or shown in Device Manager. For a PC component, note the computer or motherboard model.
- Use the manufacturer’s official support site to download a driver that matches the device, your Windows edition, and your system architecture (for example, 64-bit).
- Prefer a package intended for your Windows version rather than a generic package for a different model.
- In Device Manager, select Update driver > Browse my computer for drivers, point Windows to the downloaded package or its extracted folder, and complete the wizard.
- Restart and test. Keep the installer until you know the new driver works so you can reinstall it if needed.
Uninstall and let Windows reinstall
- In Device Manager, right-click the device and choose Uninstall device.
- Read the confirmation dialog carefully. If it offers to remove the driver package, do not select that option unless you already have a compatible replacement or Windows Update source.
- Shut down or restart Windows, then reconnect the hardware if necessary. Windows will attempt to detect it and install a basic driver.
- Check Device Manager again and install the manufacturer package if the basic driver does not provide full functionality.
Roll back after a recent driver update
If error 20 began immediately after a driver update, open the device’s Properties, select the Driver tab, and choose Roll Back Driver when the button is available. Select a reason, confirm, and restart. Rollback is unavailable when Windows has no earlier driver retained; in that case, install the earlier version from the manufacturer’s support page.
If the missing item is a disk or external drive
Inspect Disk Management
- Right-click Start and choose Disk Management.
- Locate the disk by matching its capacity and connection, not merely by its disk number.
- If it is present but has no drive letter, right-click the healthy volume, select Change Drive Letter and Paths, choose Add or Change, assign an unused letter, and test File Explorer.
- If the disk is offline, right-click its disk label and choose Online only after confirming that it is the intended device.
- If the disk shows as unallocated, unknown, or not initialized and it contains important files, stop. Initializing, formatting, or creating a new volume can make recovery harder. Check the cable, enclosure, power, and another computer first, and consult the drive manufacturer or a data-recovery professional.
A disk that is visible in Disk Management but lacks a letter is a different case from a disk absent from Disk Management. The former may be a mount or volume-configuration issue; the latter usually requires hardware, power, controller, or driver investigation.
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Use DiskPart only when you can identify the disk unambiguously
DiskPart can list disks and volumes and assign a letter, but it can also erase or alter the wrong disk. Before entering commands, disconnect other removable drives and compare the model and capacity shown in Disk Management.
- Open Windows Terminal (Admin) or Command Prompt (Admin).
- Enter
diskpart, thenlist diskto display connected disks. - Use
select disk n, replacingnonly after matching the correct capacity and model. - Enter
list volume, then select the intended volume withselect volume n. - Assign an unused letter with
assign letter=E(choose a letter that is not already in use), then enterexit.
Do not use clean, format, delete, or partition-creation commands as a trial fix. Those commands can destroy the partition information or data you are trying to preserve.
Device-specific branches
USB accessories and controllers
Test the accessory without a hub, then test a different cable and port. In Device Manager, inspect both the accessory’s category and Universal Serial Bus controllers. If several USB devices fail on the same ports, the controller, chipset driver, or physical port is more likely than all of the accessories failing at once.
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Printers and scanners
Confirm that the printer or scanner is powered on and connected by the expected USB or network path. Remove stale duplicate entries in Settings > Bluetooth & devices > Printers & scanners (Windows 11) or Settings > Devices > Printers & scanners (Windows 10), then install the model-specific package from the manufacturer. If Windows detects the device but one application cannot, select the correct device inside that application rather than repeatedly reinstalling unrelated drivers.
Network adapters
Check Device Manager > Network adapters and test whether other network devices work. Update or roll back the adapter driver, then restart. A network error that appears only in one application may be an application profile or server issue rather than a missing Windows device.
Graphics, audio, Bluetooth, and game peripherals
Use the exact model driver, not a package for a similar product. If the problem started after an update, rollback is safer than repeatedly installing unrelated versions. For Bluetooth devices, remove the pairing, restart Bluetooth, and pair again only after the adapter itself appears normally in Device Manager.
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Repair Windows software after hardware and driver checks
Run a malware scan
Use the security software already installed on Windows to perform a full scan. Malware is one possible software trigger, but this error alone does not prove that a PC is infected. Quarantine or remove anything the scan identifies, restart, and retest the device.
Check protected system files
- Open Windows Terminal (Admin) or Command Prompt (Admin).
- Run
sfc /scannowand wait for verification to reach 100 percent. - Restart Windows and repeat the device operation.
System File Checker can repair protected Windows files; it cannot repair a failed cable, enclosure, port, or storage mechanism. If it reports that it could not fix some files, preserve the exact result and continue with Windows recovery guidance rather than deleting driver files manually.
Use System Restore when the timing is clear
If the message began after a driver, application, or other installation and a restore point exists, open Control Panel > Recovery > Open System Restore. Choose a restore point dated before the change, review the affected programs, and let Windows restart. System Restore changes system files and settings, not personal documents, but you should still save work before starting.
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Reset Windows as a later recovery option
When hardware is known-good and the error persists after driver and file repairs, open Settings > System > Recovery > Reset this PC in Windows 11 (the path is similar in Windows 10). Keep my files reinstalls Windows while retaining personal files, but applications and many settings are removed. Back up important data and confirm you have installers and account credentials before choosing this option.
When to stop troubleshooting and escalate
- The device is absent from Device Manager and Disk Management on multiple ports.
- The same device fails on another computer with a known-good cable and power source.
- Windows reports CRC, read, or write faults, repeated disconnects, clicking sounds, overheating, or an enclosure that will not power on.
- A disk contains important data and appears uninitialized, unallocated, or intermittently detectable.
- The manufacturer’s compatible driver installs successfully but the hardware still cannot be detected.
At that point, contact the device manufacturer with the model, serial number, Windows edition, exact error text, additional Device Manager code, ports and cables tested, and whether another computer detects it. This evidence helps separate a replaceable cable or enclosure from a failed device and avoids destructive formatting or repeated driver changes.
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