The Base Filtering Engine is a core Windows service which is required by the Pulse Secure desktop client for Windows to operate properly. The most common reason BFE becomes disabled is by an Anti-virus program flagging BFE as a problematic service. More information about BFE can be found here:
With Pulse desktop 5.0rX and earlier, the above-mentioned errors will only occur if BFE is disabled and the Pulse “Traffic Enforcement” feature is enabled.
With Pulse desktop 5.1rX and up, the error will occur whenever BFE is disabled, regardless of the “Traffic Enforcement” status.
To resolve this issue by re-enabling BFE consult the Microsoft documentation relevant to the particular version of Microsoft Windows.