OKI MC332, MC362 and MC562 do not recognize a USB flash drive: scans are not saved, PDF files are not displayed

Last Updated on 11.08.2026 by DriverNew

OKI MC332, MC362 and MC562 MFPs allow you to save scanned documents to a USB storage device and print compatible files from it without a computer. If the device does not recognize the flash drive, does not save a scan or does not display a PDF in the print list, the cause is usually not related to the scanner or driver. Check the front USB port, the storage device file system, available space, file format and the USB Memory Interface setting.

Which models this guide applies to

Scanning to USB and printing compatible files from a USB storage device are available on the following models:

• OKI MC332dn;
• OKI MC342dn and MC342dw;
• OKI MC352dn;
• OKI MC362dn and MC362w;
• OKI MC562dn, MC562w and MC562dw;
• OKI ES3452 MFP;
• OKI ES5462 MFP and ES5462dw MFP;
• OKI MPS2731mc.

The menu item names below are given in English. If another language is selected on the control panel, use the corresponding localized items in the same menu section. The factory password for Admin Setup is aaaaaa, unless the device administrator has changed it.

First determine at which stage the problem occurs

Step 1. Connect the flash drive to the correct USB port

The storage device uses the rectangular USB Type-A connector on the front panel of the MFP. The rear USB Type-B connector is intended for connecting the OKI to a computer and cannot be used for a flash drive.

1. Wait until the MFP finishes starting and reaches the ready state.
2. Remove any extension cable, hub or additional adapter from the flash drive.
3. Connect the storage device directly to the front USB port.
4. Wait a few seconds.
5. Press SCAN and check whether USB Memory is available.
6. To check direct printing, press PRINT and find Print From USB Memory.

USB hubs and external USB drives are not supported. Storage devices with hardware encryption, biometric protection, built-in authentication software or multiple partitions may also not be recognized.

A modern USB 3.x flash drive may sometimes work in backward compatibility mode, but this is not guaranteed. For diagnostics, a basic USB 2.0 storage device without additional features is recommended.

Step 2. Check the capacity and file system

These models work with FAT12, FAT16 and FAT32 file systems. FAT32 should be used for a normal flash drive. NTFS and exFAT are not supported.

The recommended storage capacity is 4 to 32 GB. Larger storage devices are usually supplied with exFAT and may not be recognized even after a separate partition is created.

How to check the file system in Windows

1. Connect the flash drive to the computer.
2. Open File Explorer.
3. Go to This PC.
4. Right-click the flash drive.
5. Select Properties.
6. On the General tab, find File system.

If FAT32 is shown, do not format the storage device yet. Check the available space, create a simple test file and try another USB storage device. If exFAT or NTFS is shown, the storage device must be replaced or formatted as FAT32.

Step 3. Format the storage device as FAT32

1. Connect a flash drive with a capacity of no more than 32 GB to the computer.
2. Open File Explorer → This PC.
3. Note the name and drive letter of the flash drive.
4. Right-click it and select Format.
5. In File system, select FAT32.
6. For Allocation unit size, leave the default value.
7. For the first attempt, you can leave Quick Format enabled.
8. Click Start.
9. Confirm that the data will be deleted and wait for formatting to finish.
10. Open the storage device properties and check again that FAT32 is shown.

If FAT32 is not available in the list, do not use a random third-party utility and do not try to prepare a storage device significantly larger than 32 GB. For testing, use a flash drive with a capacity of 32 GB or less.

Step 4. Prepare the storage device for a diagnostic test

A large number of folders and files makes diagnostics more difficult. Start with the simplest possible structure.

1. After formatting, open the flash drive on the computer.
2. Do not create folders for the first test.
3. Copy one unencrypted PDF to the root directory.
4. Rename it to test.pdf.
5. Safely eject the storage device from the computer.
6. Connect it to the front port of the OKI.

A short name using Latin characters is used only for diagnostics. If test.pdf is displayed but the original file with a long name is not, shorten the name and remove unusual special characters from it.

Step 5. Enable USB Memory Interface

If a working FAT32 flash drive does not appear in the scan menu, the USB memory interface may have been disabled by the administrator.

1. Press SETTING.
2. Select Admin Setup and press OK.
3. Enter the administrator password.
4. Select Enter and press OK.
5. Open Management → System Setup.
6. Select USB Memory Interface.
7. Set it to Enable.
8. Save the change and return to the main screen.
9. Remove and reconnect the flash drive.

The USB Memory Interface setting primarily applies to scanning to USB. If access control is configured in the organization, the administrator may also separately restrict scanning and printing from storage devices.

If user authentication is enabled

1. Sign in on the control panel using the assigned PIN or user name and password.
2. Check whether USB Memory is available after signing in.
3. If the function is available to the administrator but unavailable to a regular user, do not change the general device settings.
4. Ask the administrator to check that user’s permissions in the access control system.

How to scan a document to USB correctly

1. Connect the tested FAT32 flash drive to the front USB port.
2. Place the original face up in the ADF or face down on the scanner glass.
3. Press the SCAN button.
4. Select USB Memory and press OK.
5. Open File Name and enter a short name. The file name must not exceed 64 characters.
6. Select the file format and resolution.
7. For the first test, select PDF and 200 or 300 dpi.
8. Press Mono for black-and-white scanning or Colour for color scanning.
9. Wait for the operation completion message.
10. Only remove the storage device after the operation has finished.

If Continuous Scan is used, do not remove the flash drive between pages. Finish adding originals on the control panel and wait until the file has been completely written.

How to choose the scan format

For the most universal result, choose a standard unencrypted PDF. The Encrypted PDF setting is intended to protect the file when it is opened on a computer, but such a file is not supported by the direct USB printing function.

What to do when USB Memory Full appears

USB Memory Full means that scanning was cancelled because there was not enough free space on the storage device. Check the flash drive first, not the MFP’s internal memory.

1. Remove the storage device after the operation has completed or been cancelled.
2. Connect it to the computer.
3. Open This PC and check the available space.
4. Copy the files you need to the computer.
5. Delete unnecessary files from the flash drive.
6. Empty the computer’s Recycle Bin while the storage device is connected: deleted files may sometimes continue to occupy space in a hidden Recycle Bin folder.
7. Repeat the scan with one page in PDF at 200 or 300 dpi.

If there is enough available space but the message appears again, the file system may be corrupted. Copy the data, format the flash drive as FAT32 or use another storage device.

How to reduce the size of the file being created

1. Reduce Resolution from 600 to 300 or 200 dpi.
2. For a text document, use Mono instead of Colour.
3. Do not select Photo for ordinary text.
4. Use stronger compression if the quality remains acceptable.
5. Split a large document into several files.
6. Test one page first, then increase the size of the job.

If the display shows only Memory Full without the word USB, there may not be enough internal memory to process a large job. Finish other jobs, reduce the resolution, reduce the number of pages and scan again.

What to do when Writing to USB memory failed appears

The message means that the MFP recognized the storage device but could not write a file to it.

1. Check whether the storage device or USB adapter has a write-protection switch enabled.
2. Connect the flash drive to the computer and try to create a small text file on it.
3. If the computer also cannot write data, disable write protection or replace the storage device.
4. Check the available space.
5. Check the file system: FAT12, FAT16 or FAT32 is required.
6. Copy the data and format the storage device as FAT32 again.
7. If the error remains, test another simple flash drive with a capacity of up to 32 GB.

Do not remove the storage device while the activity indicator is flashing or the display shows that data is being saved. If it is removed too early, USB Memory disconnected appears and the file being created may be corrupted.

Which files can be printed directly from USB

The presence of a file on the flash drive does not mean that the MFP will be able to display it in the menu. Only a limited set of formats is supported for direct printing.

How to print a tested file from USB

1. Copy a compatible file to the root folder of the FAT32 flash drive.
2. Safely eject it from the computer.
3. Connect the storage device to the front USB port of the MFP.
4. Press the PRINT button.
5. Select Print From USB Memory and press OK.
6. Select Select Print File.
7. Find the file and press OK.
8. Check the number of copies, paper feed and duplex printing.
9. Select Print and confirm the operation.

Only one file can be selected at a time. If you need to print several documents, start them one at a time.

If the PDF is not displayed in the list

1. Make sure the file extension is .pdf.
2. Move the file from a subfolder to the root directory of the flash drive.
3. Rename it to test.pdf.
4. Remove unnecessary supported files from the storage device. No more than 100 files are displayed correctly in the list.
5. Check whether the PDF is password-protected or encrypted.
6. Open the document properties in the PDF application and check its version.
7. If the version or creation method is unknown, create a compatible copy.

How to create a new copy of a problematic PDF

1. Open the original document on the computer.
2. Make sure it is displayed without errors.
3. Open the Print command.
4. Select a system PDF printer, such as Microsoft Print to PDF.
5. Save the new file with a short name.
6. Copy the new PDF to the root folder of the flash drive.
7. Test it again on the OKI.

This method creates a new printable version of the document and often eliminates incompatible encryption, a non-standard internal structure or corruption in the original PDF. Interactive forms, attachments, layers and links may be converted into normal page content when reprinted this way.

If the PDF is visible but printing does not start

1. Check the display for a paper request, tray error or consumables message.
2. Make sure the paper size selected for the job is loaded in the tray.
3. For testing, select one copy and simplex printing.
4. Try a new PDF created using a virtual PDF printer.
5. Test a small JPEG. If the JPEG prints, the USB port and flash drive are working and the problem is related to the specific PDF.
6. If no compatible file prints, test another FAT32 flash drive.

If the display shows a request for A4, Letter, Tray 1 or MP Tray, the USB storage device has already been recognized. Correct the paper size and tray settings instead of formatting the flash drive.

If one flash drive works and another does not

This result usually confirms that the MFP is working correctly. Compare the storage devices using the following criteria:

• capacity of no more than 32 GB;
• FAT32 instead of NTFS or exFAT;
• one primary partition;
• no hardware encryption;
• no authentication software;
• normal ability to write files on a computer;
• simple folder structure;
• no more than 100 supported files for direct printing.

Continue using a compatible storage device. There is no need to reinstall the printer or scanner drivers: Scan to USB and Print From USB Memory are performed by the MFP itself and do not depend on the driver installed on the computer.

When the MFP’s USB port needs to be checked

A front-port fault is possible if several tested USB 2.0 storage devices with capacities of up to 32 GB and FAT32 are not recognized, USB Memory Interface is enabled, access control does not block the function, and the same flash drives work correctly on another compatible device.

Before contacting service, record the OKI model, the message shown on the display, and the file system and capacity of the two tested storage devices. Do not attempt to straighten the contacts with metal objects or force the connector into the port: damage to the connector will require repair.