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Support Center / Troubleshooting / How to enable the base filtering engine

How to enable the base filtering engine

If the base filtering engine (BFE) is not running on your Windows device, the ProtonVPN app will show the following error messages:

Screenshot of Base Filtering Engine error message.

The most likely reason the BFE is not running is that a virus disabled it to perform malicious actions on your device.

For ProtonVPN to work properly, you will need to restart the BFE.

We explain how you can reactivate the BFE below.

For Windows 7:

  1. Open Start and type “services” into the search bar.
  2. Click on Services inside programs section.
    Screenshot of services search in Windows.
  3. Select Base Filtering Engine and then click Start. You should now be able to run ProtonVPN without issue.
    Screenshot of turning on Base Filtering Engine.

For Windows 10

  1. Download the PsTools Suite: https://download.sysinternals.com/files/PSTools.zip.
  2. Extract the zip file on to your desktop.
  3. Open the Command Prompt (CMD) with administrator privileges. In order to do so, open the Start menu -> search for “cmd” -> click on Run as administrator. (There will likely be a pop up asking you if you want to let this app make changes to your device. Click Yes.
    Screenshot of opening the command prompt.
  4. Open the extracted PsTools folder in the Command Prompt. (If you extracted the folder to your desktop, you can navigate to the PsTools folder by executing the following command in the Command Prompt window: cd C:\Users\Your User\Desktop\PSTools. Note that “Your User” represents your Windows username.)
  5. Once you have opened the PsTools folder, execute the following command in the Command Prompt: psexec -s cmd.exe
  6. Then, execute this command: sc config BFE start= auto (make sure there’s an empty space between the = sign and auto)
    Screenshot of turning on BFE in the command prompt.
  7. Restart Windows. Once your device reboots, the BFE will be restarted and you should be able ProtonVPN without issue.

If have followed these steps and are still experiencing difficulties, please contact our Support Team.

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