When trying to install or upgrade Kerio VPN client on Windows 8/8.1 machine, the installer stops and displays this error:
- Download the Kerio VPN Recovery tool
- Disable any AV running on the machine
- Unblock the installer. Right-Click the .exe, go to Properties>Unblock
- Run the .exe as Administrator
- Rerun the VPN Client installer
Kerio VPN Client is now successfully installed.