You are trying to run a newly introduced web-based VPM to edit or view policies on your ProxySG or ASG
"Failed to launch web-based VPM: The chosen editor is not supported by the reference device.
Do you want to launch the legacy VPM? "
Web-based VPM was introduced in SGOS 220.127.116.11. If your Proxy appliance is running a version prior to 18.104.22.168, the web-based VPM will not work. You can still use legacy VPM, with full functionality.
Management Center version 22.214.171.124
ProxySG or ASG with SGOS versions prior to 126.96.36.199
To take advantage of new web-based VPM, you will need to upgrade the SGOS firmware version on your Proxy to 188.8.131.52 or newer.