How to Troubleshoot Error 0x8007003B “An unexpected network error occurred” on Windows 10

Error 0x8007003b when trying to copy a large file (>100MB) over a VPN connection can occur if the connection to the server is not stable or if the configuration is not suitable, for example, if you use Samba or OpenVPN tunnels, which limit the server bandwidth.

Some users have also reported that this problem occurs on several operating systems that they copy to DFS or NAS and that changing the network settings on their device and router does not fix it.

There are things you can try to see if they fix the problem, so read on to see what you can do.

What causes error 0x8007003B “An unexpected network error has occurred”?

  • Bad sectors on the disk you are trying to copy.
  • The disk’s file system format may be set to FAT32.
  • Improperly configured network connection or server.
  • Inconsistent anti-virus software or firewall interference.
  • Viruses or malware on the system may be causing this error.
  • Certain software or hardware changes to the system can also cause this error.

How to resolve error 0x8007003B “An unexpected network error has occurred”?

Scanning for virus and malware

  1. Right-click on the Start button and select Settings from the menu.
  2. Go to Update and Security > Windows Security.
  3. In the right pane, click on Virus and Threat Protection.
  4. In the Windows Defender Security Center window that pops up, click Run new advanced scan.
  5. Select Full scan and click Scan Now.
  6. Restart your computer after the scan and try transferring the file again.

Disable the Windows scanning service

  1. Type services.MSC in the Run dialog box and press Enter to open the Services application.
  2. Find the Windows scan service and double-click it to open its properties.
  3. On the General tab, from the Startup Type drop-down menu, select Disabled.
  4. Click Apply and OK to confirm the new settings.

Disabling the Windows Firewall

  1. Press Windows + R to open the Run window, type Control Panel and press Enter.
  2. Go to System and Security > Windows Defender Firewall.
  3. In the left pane, select Turn Windows Defender Firewall On or Off.
  4. In the window that appears, select Disable Windows Defender firewall for private and public network settings.
  5. Click OK to save your changes.
  6. Then restart your computer and check if network error 0x8007003B is fixed.

Execute a system restore

  1. Press Windows + S and type restore. In the search results, click Create restore point to open the System Properties window.
  2. On the System Protection tab, click System Restore.
  3. Select the restore point that was created before the 0x8007003B network error occurred, and click Next.
  4. On the next page, confirm the restore point and click Finish to start restoring Windows.

Frequently Asked Questions

Network error 0X8007003B occurs when you transfer a large file larger than 100 MB over a VPN connection. A recently installed program/software that may have corrupted system files or misconfigured system settings. Failures caused by the built-in firewall and anti-virus program installed.

An unexpected network error has occurred. When opening a subfolder, Windows Explorer fails to display the folder contents or jumps directly to the parent folder. This behavior occurs when there are multiple levels of folders in a shared resource.

  1. Open the Control Panel.
  2. Select System and Security, then Windows Firewall.
  3. From the list of links on the left side of the window, select Enable or Disable Windows Firewall.
  4. Select Disable Windows Firewall (not recommended).
  5. Click the OK button.

  1. Scan for malware and viruses.
  2. Temporarily disable your antivirus program.
  3. Disable the Windows firewall.
  4. Disable the Windows scanning service.
  5. Run a scan of your system files.
  6. Make sure that the disk is formatted as NTFS.
  7. Scan the hard disk for file system errors.
  8. Perform a system restore.