Solution to Forticlient VPN installation issue

[rgsteele]

We had a user report that they were getting an error when trying to install the Forticlient VPN client on their Windows 11 machine. I reviewed the FortiClient00000.log (found in the user temp folder) and found a line saying

1: [08:42:24]: FCSetupWx: Failed to load C:\WINDOWS\system32\difxapi.dll

This is a DLL from the Driver Install Frameworks (DIFx) tools. These tools have been deprecated since Windows 10 version 1607, so I have no idea what the FortiFolks are doing using it in 2024. It's also a file that the installer is supposed to provide if it's not present, but the Forticlient installer appears to assume it is already on the system, hence the error.

Anyway, you can work around the issue by copying the difxapi.dll file from another machine into the C:\Windows\System32 folder.

Hope this helps someone.