How to Fix “Error 0x8007003B: An Unexpected Error Occurred”

Error 0x8007003B: An Unexpected Error Occurred

“Error 0x8007003B: An unexpected error occurred” can come up when you try to copy a large file using a network drive in Windows. It is typically caused when a third-party antivirus software or a corruption error within the system interferes with the network’s drive process.

Below, we have listed troubleshooting methods that should fix this error.

Fix #1: Disable your antivirus software

If you’re using a third-party antivirus software on your computer, there is a good chance it is preventing you from copying the file. Therefore, temporarily disabling it should prevent the error.

The steps for disabling the error depend on the antivirus you use. For example, if you’re using Avast:

  1. Right-click on the antivirus icon in the taskbar.
  2. Choose Shields control > Disable until computer is restarted.
    Disable your antivirus temporarily
    Disable your antivirus temporarily.

    Once the program is disabled, try copying the file and check if the issue is resolved.

Fix #2: Run SFC and CHKDSK Scans

If you have damaged or corrupt system files, it can cause the error code 0x8007003B. In these cases, running SFC or CHKDSK scans can help fix these files.

SFC (System File Checker) will scan protected system files on your computer for corruption errors. If any issues are identified, it will replace the corrupt files with their healthy, cached counterparts. CHKDSK (Check disk utility) will search for errors in the system drivers.

This is how you run the scans:

  1. Type “cmd” in Windows search and click Run as administrator.

    Launch CMD as an administrator
    Launch cmd as an administrator.

  2. Now, type the following command in the Command Prompt window and click Enter to execute it:
    sfc /scannow

    Perform an SFC scan
    Perform an SFC scan.

  3. Once the command is executed, execute the following command:
    chkdsk /f /r /x

    Run the CHKDSK command
    Run the CHKDSK command.

  4. Command Prompt will notify you that chkdsk cannot run because the system is currently using the targeted volume. To schedule the disk check on your next reboot, type Y, and then restart your computer.

    The command will scan your system files for potential problems on your next reboot. If any issues are identified, it will fix them automatically

Fix #3: Disable Windows Search Service

  1. Press Win + R to open a Run dialog box.
  2. Type services.msc in the text field of Run and click Enter.

    Launch Windows services using Run
    Launch Windows services using Run.

  3. In the Services window, look for Windows Search service and double-click it.

    Launch Windows Search service
    Launch Windows Search service.

  4. Go to the General tab in the Properties dialog. Expand the dropdown for Startup type and choose Disabled.

    Disable the Windows Search service
    Disable Windows Search service.

  5. Click Apply > OK to save changes. Once this is done, try copying the file again. After checking if the 0x8007003B issue has been resolved, you should reenable the service (copy the same steps above, but select Enabled instead), as keeping it disabled will prevent you from using the Search feature in Windows.

Fix #4: Change the drive’s file system type

The drive’s system type determines the types of files you can transfer to the destination drive. There are two main types in Windows: NTFS and FAT32.

If the destination drive is formatted as FAT32, you will not be able to copy and transfer files larger than 4GB.

NTFS is used for larger files; therefore, you’re less likely to encounter the 0x8007003B error. If you get the error when trying to transfer large files, try changing the destination drive system type to NTFS.

  1. Type “cmd” in Windows search and click on Run as administrator.

    Launch CMD as an administrator
    Launch cmd as an administrator.

  2. In the Command Prompt window, type the command mentioned below. Replace g with the letter of your destination drive.
    convert g: /fs:ntfs

    Convert to the NTFS format
    Convert the drive to NTFS format.

Fix #5: Edit the registry

Your system may prevent you from copying the file because it recognizes you as a guest user. In this case, you can edit a relevant value in the Registry Editor to grant yourself permission.

Here is what you need to do:

  1. Press Win + R to open a Run dialog.
  2. Type regedit in Run and click Enter.

    Launch Registry using Run
    Launch Run and type regedit.

  3. Inside the Registry Editor, navigate to the following location:
  4. Move to the right side of the window and double-click on AllowInsecureGuestAuth.Note: If you cannot locate it, right-click anywhere in the right panel and choose New > DWORD (32-bit) Value.
    Create a new DWORD value
    Create a new DWORD value.

    Rename this value as AllowInsecureGuestAuth. Then, double-click on it.

  5. Under Value data, type 1.

    Change the Value data to 1
    Change the Value data to 1

  6. Click OK to save the changes and close the Registry Editor.
  7. Finally, restart your PC to save the changes. Upon reboot, check if the 0x8007003B error is resolved.

Erik is a full-time product quality engineer at the IBM who has a passion for teaching others (and always learning) about technology. He has a Bachelor's degree in Computer Science and Engineering from Eindhoven University of Technology. Erik is the chief editor for Windows, Linux and coding tutorials.

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