Overview

When trying to install or upgrade Kerio VPN client on Windows OS, the installer stops, and displays the error 28201: device is already registered or unspecified error 0x800F020B or 0x800F0244.

This article contains instructions to resolve each of these errors in Windows 8/8.1/10 and Server 2012 environment.

Resolution

Note: please consider disabling driver signature enforcement.

Below are the steps to resolve the error with the 0x800F020B code.

Check Windows Programs and Features and uninstall the Kerio VPN client if it's listed there.
In Windows, navigate to Start > Run.
Run Regedit.
Delete this key HKEY_LOCAL_MACHINE\SOFTWARE\WOW6432Node\Kerio
Navigate to Device Manager > Network Adapter and Uninstall the Kerio Virtual Network Adapter. Alternatively, open Control Panel -> Network and Internet -> Network Connections -> right-click Kerio Virtual Network Adapter -> in Driver tab click Uninstall Device.
If you see WAN Miniport adapters, please uninstall all of them. It is normal if they are not being removed from the list after you uninstall.
Reboot the PC.
Download and Install an older version of VPN Client. You might experience the same error as on the above screenshots.
Download the Kerio VPN Recovery tool.
Disable any local antivirus running on the machine.
Run KerioVPNRecovery.exe as Administrator.
Unblock the installer.
Right-click the .exe file, go to Properties > Unblock and Run it as Admin.
You may now install the latest version of Kerio VPN Client.

Below are the steps to resolve the error with the 0x800F0244 code.

Download the attached VPN.zip file and extract it.
Navigate to Control Panel > Device Manager.
Click Network Adapters > Kerio Virtual Network Adapter.
Right-click and select Properties.
Go to the Details tab, select Inf name from the Property dropdown.
Copy the name displayed in the Value section (like oem6.inf or oem22.inf). Your name of the file might be different.
Rename the oem.inf file from VPN.zip archive to match the name from Properties menu in the previous step and copy it to C:\Windows\INF.
Copy kvnet.sys file from VPN.zip archive to C:\Windows\System32\drivers.
Try to install the latest public release again.